The provides a truck body design method and device for a railway truck. The truck body design method comprises the steps that truck body templates are obtained from a template library; a first-stage structure module forming a truck body is obtained from a first-stage module library and comprises bottom frame modules, side wall modules and end wall modules; and the first-stage structure module is assembled on the truck body templates to form a truck model. According to the truck body design method and device for the railway truck, the design workload can be reduced, the design period is shortened, and the design efficiency is improved.