Abstract: Vegetable insulating oils have been successfully applied in distribution transformers,but not applied in power transformers with higher voltage levels.Due to the fact that the viscosity of vegetable insulating oil is greater than that of mineral insulating oil,it is necessary to investigate the impregnation characteristics of vegetable insulating oil in transformer boards.The test model of rapeseed insulating oil-paper insulation impregnation was designed and the impact of oil-paper insulation impregnated with the process of the main factors was discussed based on the analysis of impregnation mechanism of oil-paper insulation.The impregnation characteristics of rapeseed insulating oil were obtained by testing and compared with that of mineral insulating oil.The results show that rapeseed insulating oil-paper insulation impregnated can reach the standards of mineral insulating oil by increasing the impregnation temperature.