Abstract: The new aluminum alloy casting material was used for the thin-walled shell of hydraulic pump, where the trace addition of Ni was added into the ZL101A alloy. The low pressure casting process was numerically simulated with ProCAST casting simulation software. And the time to solidus, shrinkage and porosity during the casting solidification were predicted by the results of temperature and flow fields simulations. Aluminum alloy pump shell casting was manufactured according to the actual engineering process, and specimens obtained from the casted pump shell were carried by the isothermal hot compression tests. The structural deformation mechanism and microstructural characteristics of compression specimens at different rates and temperatures were analyzed. The reasonable pouring temperature and heat treatment technique will be used to guide the investment casting process design. Then the shrinkage and porosity of shell castings can be effectively controlled, and the investment casting quality of the Al-Si based thin-walled shell can be improved.