Objective:To observe the tocolysis efficacy of prescription of nourishing kidney, activating blood and resolving phlegm in polycystic ovarian syndrome (PCOS) with threatened abortion patients with syndrome of kidney deficiency and phlegm dampness and syndrome of kidney deficiency and blood stasis. Methods 149 PCOS patients with threatened abortion were randomly divided into the group A (50 cases), group B (47 cases) and group C (52 cases). The group A was treated with prescription of nourishing kidney, activating blood and resolving phlegm. The group B was treated with progesterone injection. The group C was treated with prescription of nourishing kidney, activating blood and resolving phlegm combined with progesterone injection. All the groups were treated until pregnancy for 12 weeks, the clinical efficacy and tocolysis efficacy were observed, and the pregnancy outcome was followed up. The changes on TCM syndrome score and serum levels of human chorionic gonadotropin (HCG), progesterone (P), human insulin like growth factor binding protein-1 (IGFBP-1) and plasminogen activator inhibitor-1 (PAI-1) were compared.  Results:①Finally 146 cases completed the trial, among 49 cases in the group A, 45 cases in the group B and 52 cases in the group C. ②The total effective rates were 85.71% in the group A, 64.44% in the group B and 88.46% in the group C. There was statistically significant difference on the clinical efficacy among the groups (P<0.05). There was no statistically significant difference on the clinical efficacy between group A and group C (P>0.05), however, the clinical efficacy of group A and group C was both better than that of group B (P<0.05). ③At the end of treatment, the numbers of effective tocolysis were 42 cases (85.71%) in the group A, 29 cases (64.44%) in the group B and 46 cases (88.46%) in the group C. There was no statistically significant difference on the effective rate of tocolysis between group A and group C (P>0.05), however, the effective rate of tocolysis of group A and group C was both higher than that of group B (P<0.05). ④During the trial, the abortion rates were 16.33% in the group A, 40.00% in the group B and 11.54% in the group C. There was no statistically significant difference on the abortion rate between group A and group C (P>0.05), however, the abortion rate of group A and group C was both lower than that of group B (P<0.05). ⑤After treatment, there was no statistically significant difference on TCM syndrome score between group A and group C (P>0.05), however, the TCM syndrome score of group A and group C was both lower than that of group B (P<0.05). ⑥Compared with treatment before (pregnancy for 5 weeks), the serum HCG level was significantly increased in all groups after treatment (pregnancy for 6,7, 8 and 9 weeks) (P<0.05). After treatment, compared with previous gestational week, the serum HCG level was significantly increased at different gestational weeks (P<0.05). After treatment, the serum HCG level in the group A and group C was significantly higher than that in the group B at each gestational week (P<0.05), and the serum HCG level in the group C at sixth and seventh gestational week was significantly higher than that in the group A (P<0.05). ⑦Compared with treatment before, the P level was significantly increased in the group B and group C after treatment (P<0.05); however, in the group A, there was no statistically significant difference on P level between treatment before and after(P>0.05). After treatment, there was no statistically significant difference on P level between group B and group C (P>0.05). Compared with group A, there was statistically significant difference on P level in the group B and group C, respectively (P<0.05). ⑧Compared with treatment before, the IGFBP-1 level was significantly increased (P<0.05) and the PAI-1 level was significantly decreased (P<0.05) in the group A and group C after treatment. In the group B, there were no statistically significant differences on the levels of IGFBP-1 and PAI-1 between treatment before and after (P>0.05). After treatment, there were no statistically significant differences on the increase level of IGFBP-1 and decease level of PAI-1 between group A and group C (P>0.05). Compared with group B, there were statistically significant differences on the increase level of IGFBP-1 and decease level of PAI-1 in the group A and group C, respectively (P<0.05).  Conclusion:Prescription of nourishing kidney, activating blood and resolving phlegm shows better tocolysis efficacy in PCOS with threatened abortion patients with syndrome of kidney deficiency and phlegm dampness and syndrome of kidney deficiency and blood stasis, which can effectively regulate the levels of HCG, IGFBP-1 and PAI-1, improve the clinical symptoms, reduce the occurrence of spontaneous abortion and enhance the ongoing pregnancy rate and live birth rate, and thus improve the pregnancy outcome. Furthermore, for the PCOS patients with threatened abortion whose P level was lower and luteal function was insufficient, this prescription and progestin can be used simultaneously for tocolysis to achieve complementary advantages of traditional Chinese and western medicine.