This paper deals with both the leading train and the following train in a train tracking under a four-aspect fixed autoblock system in order to study the optimum operating strategy for energy saving.After analyzing the working principle of the four-aspect fixed autoblock system,an energy-saving control model is created based on the dynamics equation of the trains.In addition to safety,energy consumption and time error are the main concerns of the model.Based on this model,dynamic speed constraints of the following train are proposed,defined by the leading train dynamically.At the same time,the static speed constraints defined by the line conditions are also taken into account.The parallel genetic algorithm is used to search the optimum operating strategy.In order to simplify the solving process,the external punishment function is adopted to transform this problem with constraints to the one without constraints.By using the real number coding and the strategy of dividing ramps into three parts,the convergence of GA is accelerated and the length of chromosomes is shortened.The simulation result from a four-aspect fixed autoblock system simulation platform shows that the method can reduce the energy consumption effectively in the premise of ensuring safety and punctuality. This paper deals with both the leading train and the following train in a train tracking under a four-aspect fixed autoblock system in order to study the optimum operating strategy for energy saving. After analyzing the working principle of the four-aspect fixed autoblock system, an energy-saving control model is created based on the dynamics equation of the trains. addition to safety, energy consumption and time error are the main concerns of the model. Based on this model, dynamic speed constraints of the following train are proposed, defined by the leading train dynamically. At the same time, the static speed constraints defined by the line conditions are also taken into account. parallel genetic algorithm is used to search the optimum operating strategy. In order to simplify the solving process, the external punishment function is adopted to transform this problem with constraints to the one without constraints.By using the real number coding and the strategy of dividing ramps into thre the convergence of GA is accelerated and the length of chromosomes is shortened. The simulation result from a four-aspect fixed autoblock system simulation platform shows that the method can reduce the energy consumption effectively in the premise of ensuring safety and punctuality.