Abstract: As an environmentally friendly liquid dielectric with a high flash point, vegetable insulating oil is considered to be a good substitute for mineral insulating oil. In order to compare the effect of the composition type of oil-paper insulation on charge transport, four different oil-immersed paper samples were prepared including one type of mineral insulating oil, one type of vegetable insulating oil and two types of cellulose insulating papers. Epoxy was used as a barrier layer to construct a double-layer configuration with one blocking layer and a triple-layer configuration with the test sample sandwiched between two blocking layers, the space charge distribution of which was measured by the pulsed electro-acoustic (PEA) method, and the mobility of positive and negative injected charges in different oil-immersed papers was further obtained. The results show that the effect of insulating oil type on charge transport is more significant than that of insulating paper type. For oil-immersed paper composed of the same type of insulating oil, the conductivity and injected charge mobility are very close. The conductivity and charge mobility of the vegetable oil-immersed paper samples are much higher than those of the mineral oil-immersed papers, and the conductivity disparity between vegetable oil-immersed paper and mineral oil-immersed paper comes not only from the difference in charge mobility but also from the difference in carrier concentration.