Objective: To compare the transferring efficiency and killing effects of one time and continuous mediation with GE7,a non-viral targeted delivery system,in transfection of thymidine kinase gene of herpes simplex virus (HSV-tk) into ovarian cancer cells. Methods: GE7 was used to prepare recombinants with β-galactosidase (β-gal) and HSV1-tk; the re-combinants were then used to transfect human ovarian cancer line CaOV3 once and continuously. β-gal staining was used to compare the efficiencies of one time and continuous mediation with GE7 system. Ganciclovior (GCV) was introduced into HSV1-tk transfected ovarian cells. Through drawing the cell growth curve and flow cytometry,the killing effects of GCV on once and continuously GE7/HSV1-tk transfected cells were observed. Results: We found that the one time and continuous exogenous gene transfer efficiencies were about 80% and 85%,respectively. When 1μg/mL GCV was used to treat ovarian cell transfected with HSV1-tk gene,growth inhibiting rates of ovarian cells of one time and continuous transferring were 82% and 90%,respectively; their apoptosis indices were 15 and 30,respectively. Under same GCV concentration,continuous me-diation of GE7/pCMV-tk transfection into ovarian cancer cells had more significant inhibitory effect than one time mediation (P<0.05). Conclusion: Compared with one time mediation,continuous mediation of transfection with GE7 gene delivery system has higher efficiency. Continuous mediation of GE7/HSV1-tk/GCV therapeutic gene system has more powerful killing effect. Objective: To compare the transferring efficiency and killing effects of one time and continuous mediation with GE7, a non-viral targeted delivery system, in transfection of thymidine kinase gene of herpes simplex virus (HSV-tk) into ovarian cancer cells. Methods: GE7 was used to prepare recombinants with β-galactosidase (β-gal) and HSV1-tk; the re-combinants were then used to transfect human ovarian cancer line CaOV3 once and continuously. β-gal staining was used to compare the efficiencies of one time and drawing in the cell growth curve and flow cytometry, the killing effects of GCV on once and continuously GE7 / HSV1-tk transfected cells were observed. Results: We found that one of the time and continuous exogenous gene transfer efficiencies were about 80% and 85%, respectively. When 1 μg / mL GCV was used to treat ovarian cell transfected with HSV1-tk gene, growth inhibiting rates of ovarian cells of one time and continuous transfer were 82% and 90% respectively, respectively; their apoptosis indices were 15 and 30, respectively. Under the same GCV concentration, continuous me-diation of GE7 / pCMV-tk transfection into ovarian cancer cells had More significant inhibitory effect than one time mediation (P <0.05). Conclusion: Compared with one time mediation, continuous mediation of transfection with GE7 gene delivery system has higher efficiency. powerful killing effect.