The optimization model of topology is a kind of important model in network, which can effectively optimize the overall link performance of the system. In Ethernet topology of electromagnetic launch system, some nodes and links are overloaded, once the blockage occurred, the performance of the key links in the network can be affected. To solve this problem, a multi-objective programming model for optimizing Ethernet topology was established and the genetic algorithm based on genetic ring operation was designed to solve the model. The simulation was carried out to obtain the optimal Ethernet topology. Default parameters of corresponding network nodes in the practical system were modified through simulation and calculation. The result shows that the model and the algorithm can effectively balance load, reduce conflict rate and optimize the topology without changing the physical link by adding cost, which is of universal significance to electromagnetic launch system.