Reducing the traction energy consumption plays an important role in railway energy saving. Viewed from the present research situation--the models were all based on the train without energy-feedback, moreover the line condition is the fixed steep down or steep up grades, the train group energy control strategy on continuous change gradient steep downgrades with the energy-feedback is proposed. The advantage for energy-saving of the strategy is proved through the traction calculation in theory. On that basis the optimization method is applied to get the optimal strategy balancing the operation time and energy consumption. By comparing the traditional control strategy with the optimal control strategy, the experiments show that the optimal overall target index of the operation time and energy consumption is much better.