In order to extend the application range of single-sided permanent magnet disk generator, the optimization design of such generator is investigated. Firstly, the generator suitable for vehicle operating conditions is selected as the research object after analyzing the influence of permanent magnet thickness, air gap and shape on the generator, and comparing the performance of the generator with or without iron core. Then, a multi-objective optimization equation is established with the thickness and shape of permanent magnet as optimization variables, and the voltage waveform distortion rate and efficiency as optimization objectives by response surface method. The results show that thickness and shape of permanent magnet have significant influence on the generator performance. The efficiency of single-sided permanent magnet generator after response surface optimization is improved by 0.83%, and the total harmonic distortion (THD) is reduced by 16.7%. The optimization method has a certain reference value in the design of permanent magnet structure of single-sided disc generator.