The structure of the pump case was studied. Two plans for the pump case-two-gate system and three-gate system were designed based on its features including thin wall, deep cavity and easy to lack of the material in the edge as well as easy for deformation and heat accumulation. Through the comparison of the two plans in filling time, plastic flow front temperature and cavitation with Moldflow software, a three-gate plan was selected which utilizes one main runner and three second and third subchannel evenly distributed as the gating system of the pump case. In this plan, while injection, the injection pressure was 63. 9532 MPa and the clamping force was 47. 5293 t. On this base, a five-loop cooling system of the injection mold was created, and the pump shell buckling deformation was analysized. Warping deformation caused by mold cooling and material orientation was almost zero.