Abstract: In view of the unreasonable maintenance of multi-unit equipment in natural gas pipeline system, in order to lower the maintenance cost and improve the availability of the system effectively, a multi-unit equipment group maintenance strategy was introduced to determine whether each component needs preventive maintenance or replacement. According to the rolling horizon approach, a group maintenance model for the multi-unit equipment of natural gas pipeline was established while the lowest availability of the system operation was ensured. In this model, the total maintenance cost saving maximization of the system is taken as the objective and in view of the change of maintenance environments, the limited maintenance human resource is taken as the constraint. It provides the theoretical basis for determining the optimal group maintenance strategy. Finally, Multifit algorithm and genetic algorithm were integrated to simulate and solve the optimal group maintenance plan of each component in the compressor of the natural gas pipeline system based on the specific application cases. It is indicated that by virtue of this model, the maintenance cost can be saved to the uttermost, the maintenance can be grouped reasonably and the optimal maintenance time can be determined.