Abstract: In order to optimize fuel injection results of the electronically-controlled pressure-accumulation system for diesel engines, the optimization of its parameters including structure parameters and function parameters is required. The number of related parameters is large and complex relation between them is present. According to numerical simulation of the working process, based on the simple genetic algorithm (SGA), some types of improved genetic algorithms are applied to optimize the parameters. In this paper, the process of the parameter optimization designed for each improved genetic algorithm (GA) is explained briefly and discussed in many of its respects. The optimized results show that, in the total number of the largest fitness, AGA is 355 times more than SGA, AORGA is 392 times more than it, and REGA is 397 times more than it.