Abstract: In this paper, loss characteristics of a high-efficiency light-weight VLF-PM motor under different operation condition were investigated. The iron loss characteristics of VLF-PM motor were researched by analyzing the variation of magnetic density under different working conditions. Firstly, the equivalent magnetic circuit was analyzed, and the mathematical relationship between flux density and iron loss was established. Then, the influence of relevant parameters on the iron loss was analyzed by response surface method, and the optimal design of VLF-PM motor was determined. The iron loss characteristics of the motor before and after optimization were analyzed and compared by using finite element method. Finally, the optimal motor was built and tested to verify the validity of the research on the iron loss characteristics and low-loss-design of high-efficiency light-weight VLF-PM motor under multiple working conditions, offering a potential research path for the research of high-efficiency light-weight motors.