The energy-saving demand of urban rail transit industry and the development of Chengdu metro was introduced. Taking Chengdu metro line 10 as an example, the optimal design scheme of the application of permanent magnet synchronous motor traction system in metro field was expounded, and the energy-saving and economic benefit expectation of the permanent magnet synchronous motor traction system was analyzed in Chengdu metro. According to the simulation calculation, the energy saving rate of permanent magnet traction train can reach 25% - 28% under the condition of full regeneration energy feedback.