In order to realize the real-time and accurate prediction of the transient temperature rise of gas insulated switchgear (GIS) and meet the requirements of digital operation and maintenance, a single-phase GIS transient temperature rise prediction model based on multiple relaxation lattice Boltzmann method (MRT-LBM) is proposed in this paper, which realizes the real-time prediction of the thermal-flow coupling field inside GIS and the study of the heat transfer characteristics inside GIS under different Rayleigh numbers (Ra). Firstly, the D2Q9 lattice model is used to solve the gas flow and thermal lattice Boltzmann equation in GIS at the mesoscopic scale. The obtained GIS temperature rise results are compared with the finite volume method (FVM). The maximum relative error is 4.53%, which verifies the validity of the model. Secondly, the model is used to simulate the heat transfer of GIS internal field under different Rayleigh numbers. It is concluded that with the increase of Rayleigh number, the convective heat transfer inside GIS is enhanced and the temperature rise is reduced. Finally, the simulation model based on MRT-LBM proposed in this paper provides a reference for the real-time monitoring of GIS temperature rise and the study of thermal-fluid coupling heat transfer process under different Ra.