Abstract: The electrical connectors are widely used in the electronic equipment. But the humid conditions will make its insulation reliability fall and cause frequent connector malfunctions. As a result, the reliability of the electronic equipment is badly affected. The effect of jointing process and cleanout process on the insulation of the electrical connector are studied in this paper by testing the insulation in normal conditions and humid conditions and operation performance of the rectangular connector. In addition, different kinds of insulation-seal technics are also studied to validate their effect on insulation.