The casing heater can also maintain the wellbore formation while maintaining the stability of the pore wall to prevent the formation of secondary hydrates in the well during the hydrate production process. In order to analyze the influence of daily water production, gas-water ratio and heating power on the temperature distribution in the well formation during the hydrate production process, the heating process was simulated by COMSOL Multiphysics. The simulation results show that the effect of water production rate on the heating effect is obviously greater than the heating power. The heating power mainly affects the formation temperature of the near-well section, and the gas-water ratio mainly affects the heating radius. The numerical simulation is used to analyze and evaluate the heating effect of casing heater, which is of guiding significance for the economical and efficient mining of natural gas hydrate.