The invention discloses a vehicle assembly method. Annular conveying lines are respectively arranged on the side of a main production line corresponding to all procedure positions; assembly parts needing to be assembled can be put on positioning devices capable of moving on the annular conveying lines; the positioning devices circularly move on the annular conveying lines until the positioning device on the foremost side reaches a grabbing position; positioning mechanisms on the annular conveying lines are acted to lock and fix the positioning devices to accurately position in the grabbing position; a manipulator of the main production line can automatically grab the assembly parts positioned on the positioning devices in the grabbing position; and the assembly parts are shifted and positioned on assembled parts on the main production line; and an automatic assembly mechanism on the main production line is acted to automatically assemble the assembly parts on the assembled parts to finish automatic assembly. The vehicle assembly method can greatly reduce assembly workers of the production line, improves the working efficiency of the assembly workers, eliminates personal injury accidents of the assembly workers, and meanwhile, facilitates realization of mixed line assembly of multiple vehicle types.