Abstract: Based on the original casting process, optimization of sand casting process for QT600-3 caliper castings was conducted by orthogonal simulation experiment. The potential locations of shrinkage porosity and shrinkage cavity defects in the casting were predicted and the effects of pouring temperature, pouring speed and number of internal runners on the shrinkage and shrinkage defects were systematically analyzed based on the orthogonal experimental results, and an optimal casting process scheme was obtained, which can effectively predict and control the defect distribution of the QT600-3 caliper castings, and significantly reduce the rate of shrinkage porosity and shrinkage cavity defects, providing an important reference for the process design of similar castings.