With full consideration of metro train dynamic characteristics, line conditions, speed limit in the interval, punctuality and so on, the multi-constraints energy consumption model based on utilization of regenerative braking energy was established according to the modern optimal control theory. Then the model of train energy consumption was solved by means of immuneparticle swarm optimization algorithm, the energy saving operation conditions and the switching points were obtained. Finally, the minimum energy consumption of train at the station was obtained. In order to verify the effectiveness of the method, the Nanning metro line 1 was simulated as an example, and the energy consumption was reduced by 6.62% after optimization.