The present invention discloses an assessment method of an insulation performance of a bushing capacitor packet under temperature change. The method comprises the steps of: designing a device for testof the insulation performance of the bushing capacitor packet under temperature change, wherein a control device compares the average oil temperature where the bushing capacitor packet is located collected by a temperature sensor and a set oil temperature to control the working states of a direct current source, a condensation water tank and an oil pump to change the average oil temperature wherethe capacitor packet is located so as to assess the insulation performance of the bushing capacitor packet. The assessment method of an insulation performance of a bushing capacitor packet under temperature change simulate the operation work conditions of the insulation bushing in a condition that a high-speed railway loads high-frequency in the daytime and low-frequency at night in an alpine region so as to allow the method to more really and accurately assess the actual insulation performance of the bushing.