This paper proposes a transient thermal analysis model for a nitrogen-cooled cryogenic system used in superconducting electromagnetic suspension magnets. First, the structural parameters of the nitrogen cryogenic system and the internal high-temperature superconducting magnet are detailed. Subsequently, temperature change simulations during the system's cooling process using a cryocooler, as well as during the cooling and nitrogen-insulation process, were conducted using COMSOL software. Finally, simulations of the temperature variations during the system's offline operation were performed. This study provides valuable references for the design and optimization of nitrogen-cooled cryogenic systems.