Objective: To observe the effects of external application of Hongzhongxiao Tincture,a drug for encircling lesion,on the C reactive protein(CRP)and procalcitonin(PCT)in plasma and matrix metalloproteinase-2(MMP-2)in secretion and the histopathology at different locations around the abscess in rats with skin abscess under the guidance of defended field theory. Methods40 rats were divided into the blank group,pretreatment group,treatment group,control group and model group. Except the blank group,the subcutaneous abscess model was established by subcutaneous injection of Staphylococcus aureus in the other four groups. After modeling,the rats were treated with different drugs. On the 3rd,7th and 14th day of treatment,the cardiac blood at volume of 1.5 ml was collected in each group. Except the rats in the control group,100 μl 0.9% NaCl solution was used for other rats to rinse the wound and then the wound secretion was recycled. The levels of CRP and PCT in plasma and MMP-2 in secretion were detected by enzyme linked immunosorbent assay(ELISA). The rats were sacrificed after treatment for 14 days,and the subcutaneous tissues at 1 cm,2 cm and 3 cm around abscess were extracted respectively and made into sections for Masson staining. The inflammatory cell infiltration,vascular proliferation and telangiectasia in skins and muscles at different locations around abscess were observed under the microscope.  Results:In different treatment periods,the plasma levels of CRP and PCT in the model group,control group,pretreatment group and treatment group showed the decreasing tendency and were higher than those in the blank group,and tended to be stable at the end of the treatment. During the treatment periods,the plasma levels of CRP and PCT in the pretreatment group and treatment group(both treated with Hongzhongxiao Tincture by external application)were lower than those in the control group and model group to varying degrees. In the early stage of the treatment(3rd and 7th day),there were statistically significant differences on the plasma levels of CRP and PCT between the control group(treated with Mupirocin Ointment by external application)and pretreatment group or treatment group(P<0.05,P<0.01). On the 14th day of treatment,the plasma levels of CRP and PCT in the pretreatment group and treatment group were close to those in the control group,with no statistically significant differences(P>0.05). In the middle and late stage of the treatment(7th and 14th day),the MMP-2 level in wound secretion in the pretreatment group and treatment group was lower than that in the model group and control group,with statistically significant differences(P<0.05,P<0.01). The pathology of tissues around abscess under the microscope showed that the inflammatory cells infiltration in the subcutaneous muscle at different locations around abscess in the treatment group and pretreatment group was significantly lower than that in the control group and model group.  Conclusion:The therapy of encircling lesion with Hongzhongxiao Tincture is applied in the treatment of rat skin abscess,which can alleviate inflammatory infiltration in tissue around abscess and improve the systemic and local infection by reducing the levels of CRP and PCT in plasma and MMP-2 level in secretion,and thus provide favorable conditions for the formation of defended field.