In the process of power compensation of the superconducting magnetic energy storage system (SMES) in the power grid, the existence of ac loss and eddy current loss will cause the magnet to heat up, and temperature rise is the main factor limiting the power output capability of SMES. This article proposes a state assessment method (SAM) that considers the temperature rise of the magnet. This method comprehensively considers the effects of the initial operating current ( I 0 ), initial temperature ( T 0 ), power response time ( t ), and output voltage ( U ) of the magnet on the temperature rise. Before SMES responds to the system power command, a magnet temperature estimation link is added to adjust the power command according to the magnet's possible temperature rise so as to ensure the magnet's safety. By simulating the operating conditions of 150 kJ/100 kW SMES in the microgrid, it is proved that the magnet's thermal stability is significantly improved after adding SAM, and the system operating parameters still meet the requirements within a particular response time. This method helps to maximize the power response potential of SMES under the premise of protecting the safety of the magnet.