A test apparatus that testing for the electrical insulation properties of the insulation systems under 0.1 MPa helium and air environment respectively was designed. Partial discharge inception voltage (PDIV), corona inception voltage, interturn impact, insulation resistance and power frequency breakdown voltage of insulation system model for helium circulator drive motor under 0.1 MPa helium and air environment respectively were tested. Test showed that some insulating properties of the insulation system in helium environment dropped significantly compared with that in the air environment at 0.1 MPa pressure, PDIV of insulation system in helium environment is about 50% of that in the air environment, corona inception voltage of insulation system in helium environment is about 20% to 25% of that in the air environment, flashover breakdown voltage of insulation system in helium environment is about 50% of that in the air environment.