Abstract: Aiming at frame structure consistency problems of agricultural tricycles in domestic market, a new structural optimization design for an agricultural tricycle frame was carried out．Taking girder frame as a research object, topology optimization and size optimization methods were combined with finite element analysis．Manufacturing process and economy were fully considered during design process．On the basis of satisfying original performance of frame, a new truss-type tricycle frame met current market demand was designed, which has certain reference value for lightweight design of other vehicle frames．