We chose Hela cells as research object and studied the cytotoxicity generated by cyclophosphamide, an antitumor drug, after cell electroporation by the use of electromagnetic pulses. Comparison between the electroporation group and the contrast group revealed the greatly enhanced cytotoxicity of the electroporation group, indicating that under some conditions electromagnetic pulses can enhance the cytotoxicity of antitumor drugs. The results of this study provide reliable evidences and a feasible approach for clinical treatment of tumor.