Objective:To discuss the influence of Shiquan Dabu Decoction and its separated recipe Sijunzi Decoction on the metastatic tumor growth and natural killer(NK)cells in BALB/c mice transplanted with CT-26 colon carcinoma after resection of primary tumor,and study the possible mechanism. MethodsThe subcutaneous metastatic tumor model of CT-26 colon carcinoma was established in BALB/c mice. The mice were randomly divided into the un-resection group of primary tumor,resection group of primary tumor,Shiquan Dabu Decoction group and Sijunzi Decoction group,12 mice in each group. From 5 days before the operation,the mice in the un-resection group and resection group were treated with 0.9% NaCl solution by intragastric administration,each mice in the Shiquan Dabu Decoction group were treated with Shiquan Dabu Decoction at dose of 0.52 g,each mice in the Sijunzi Decoction group were treated with Sijunzi Decoction at dose of 0.18g,with a course of continuous 2 weeks. Except the un-resection group,the resection of primary tumor was performed in the other groups. The expression of adhesion molecule CD49b in metastatic tumor was detected by Supervision immunohistochemistry. The percentage of NK cells expressing CD49b and CD335 in peripheral blood lymphocytes were measured by flow cytometry.  Results:The incidence rate of metastatic tumor was 75% in the resection group,58% in the un-resection group,42% in the Shiquan Dabu Decoction group and 58% in the Sijunzi Decoction group. 2 weeks after operation,the weight of metastatic tumor in the Shiquan Dabu Decoction group was obviously lower than that in the un-resection group and resection group ,with statistically significant differences(P,<,0.05),but no significant effect on the weight of metastatic tumor was observed in the Sijunzi Decoction group. The volume of metastatic tumor in the Shiquan Dabu Decoction group [(1 546.79±242.13)mm,3,] and Sijunzi Decoction group [(2 079.24±234.10)mm,3,] was significantly lower than that in the un-resection group [(2 412.98±230.42)mm,3,] and resection group [(3 065.06±317.02)mm,3,],with statistically significant differences(P,<,0.01).The proportion of CD49b expressing NK cells in peripheral blood was(20.63±2.99)% in the un-resection group,(22.74±1.05)% in the resection group,(34.34±3.77)% in the Shiquan Dabu Decoction group and(28.50±1.65)% in the Sijunzi Decoction group. The proportion was obviously increased in the Shiquan Dabu Decoction group and Sijunzi Decoction group,with statistically significant differences(P,<,0.05).The proportion of CD335 expressing NK cells in peripheral blood was(2.19±0.69)% in the un-resection group,(1.90±0.21)% in the resection group,(3.21±0.19)% in the Shiquan Dabu Decoction group and(2.36±0.26)% in the Sijunzi Decoction group. The proportion was obviously increased in the Shiquan Dabu Decoction group,the difference was statistically significant compared with the other groups(P,<,0.05).The results of immunohistochemistry showed that the CD49b expression in the metastatic tumor in the Shiquan Dabu Decoction group was significantly higher than that in the other groups(P,<,0.05).  Conclusion:The resection of primary tumor can inhibit the function of NK cells and down-regulate the expressions of CD49b and CD335,which is beneficial to tumor cell escape and growth. Shiquan Dabu Decoction can significantly inhibit the growth of metastatic tumors after resection of primary tumor,which may be associated with the up-regulation of CD49b and CD335 expressions.