The invention provides a device for simulating reactor core decay heat of a nuclear power station. The device is characterized by comprising a body (1), a three-phase self-coupling transformer (2) and a three-phase general-purpose converter (3), wherein the body (1) sequentially comprises an annular fixed inner wall (11), a thermal insulation layer (12), an inner insulation layer (13), an induction coil (14), an outer insulating layer (15) and a protective layer (16) from inside to outside; and the three-phase self-coupling transformer (2), the three-phase general-purpose converter (3) and the induction coil (14) are sequentially connected with one another. The invention further provides a method for simulating reactor core decay heat of the nuclear power station. According to the device for simulating the reactor core decay heat of the nuclear power station provided by the invention, industrially general three-phase self-coupling transformer and the three-phase general-purpose converter are utilized as main control instruments, so that the process is easy, the operation is simple and convenient, and the electric heating power required by simulation of the reactor core decay heat of the nuclear power station can be met; a foundation is laid for research on the effect on a reactor core caused by the nuclear power station; and the device and the method have wide industrial application prospects and scientific research value.