Objective To study the effect of combining recombinet interferon α -2b gel and loop electrosurgical excision procedure (LEEP) to treat cervical intraepithehal neoplasia (CIN). Methods Prospective, randomly and control study was progressed in 80 patients with CIN Ⅱ-Ⅲ. Before carrying out LEEP, all women were performed high-risk HPV DNA detection by the method of HC2. Among them, forty women were. assigned to be the study group, in which the patients were added to use recombinet interferon α -2b gel for three courses of treatment before and after LEEP, the other forty women who carried out LEEP simply were assigned to be the control group. All patients were examined by hquid-based thinprep cytology test (TCT) and colposcopic site-specific biopsies to doubtful focus of infection in the 3rd, 6th, 9th and 12th month after treatment, and judged the effect by using HC2 in the 6th and 12th month after treatment. Results Eighty patients were not detected residue and recidivafion of CIN diagnosed by coiposcopic site-specific biopsies to doubtful focus of infection. In the study group, 3 women were abnormal detected by TCT, 37 women were negative detected by HC2, the negative rate was 92.5% when LEEP ended 6 months. The cure rate was 100.0% when LEEP ended 12 months. In the control group, 21 women were abnormal detected by TCT, 19 women were negative detected by HC2, the negative rate was 47.5% when LEEP ended 6 months, 8 women were negative detected by TCT, 25 women were negative detected by HC2, the cure rate was 62.5% when LEEP ended 12 months.In the 6th and 12th month after LEEP, the difference was distinguished in the cure rate between two groups. Conclusions There is double interrupted effects by combining recombinets interferon α -2b gel and LEEP to treat CIN. It can raise the one-time cure rate of the patients with CIN.