The invention provides a device for simulating heating of a power device and a system for testing performance of a cooler. The device for simulating heating of the power device comprises a substrate,a shell arranged on the substrate, a first insulating layer, a second insulating layer, a first copper plate, a lining plate, a second copper plate, a heating piece, a spring lead, a printed circuit board, a positive electrode busbar terminal and a negative electrode busbar terminal, wherein the shell and the substrate form an accommodating cavity; the first insulating layer and the second insulating layer fill the accommodating cavity from bottom to top; the first copper plate is arranged in the first insulating layer in an immersed mode and is also arranged on the substrate; the lining plateis arranged on the first copper plate; the second copper plate is arranged on the lining plate; the heating piece is arranged on the second copper plate; the spring lead is arranged on the second copper plate; the printed circuit board is arranged on the spring lead; the printed circuit board is located above the heating piece; the heating piece and the second copper plate are connected through an ultrasonic lead; and one end of the positive electrode busbar terminal and one end of the negative electrode busbar terminal are connected with the second copper plate, and the other ends extend outof the shell to be connected with an external power supply. The device can better simulate heating of a packaging device to judge the performance of the cooler.