The assembly quality of automobile gearbox affects the performance of automobile,in order to achieve higher efficiency and better quality of gearbox assembly,and can trace the root cause,the use of flexible assembly line for production.First of all,according to the production of the composition and characteristics of the gearbox flexible assembly line is analysed,based on which a brief study of the assembly station;PROFIBUS fieldbus control and PLC research and analysis,the control system design,and through simulation to verify the feasibility of the flexible assembly line,to lay the foundation for the further implementation of the flexible assembly line for the gearbox.