With the increasing construction of underground power cable tunnels for energy transmission, the fans in tunnels, used for ventilation, consume great deal of electric energy. Due to the lack of scientific planning, a large number of energy is unnecessarily consumed. This paper proposes an optimal planning method for fan operation based on cable conductor temperature. The improved flow field parameters are used to calculate the cable temperature, which is validated by finite element method (FEM). The conductor temperature is then taken as the constraint condition for fan operation planning. Based on the load forecasting, a variety of fan operation schemes are obtained. The improved particle swarm optimization (PSO) algorithm is implemented to obtain the optimal operation scheme such that the cable conductor temperature does not exceed the allowable value and the fan power consumption is minimum. The energy consumption of the fan after planning is only 18.1% of the original one in the best case for the studied scenario. To solve the load forecasting error problem, this paper adopts model predictive control (MPC) to replan the optimal operation scheme of the fan dynamically. The results show that the optimal planning scheme can always be guaranteed.