Hot cracking easily occurs in the semi-continuous casting of 2024 aluminum alloy, further seriously affecting its industrial production and comprehensive performance. Numerical simulation technology is an important method to solve the problem of hot cracks. The CAFE (cellular automata finite element) module of ProCAST casting analysis software was used to simulate the solidification microstructure. First, the macroscopic temperature field of the semi-continuous casting process is simulated by the moving boundary method. Macroscopic temperature fields are used for microstructure simulation. The actual grain size is consistent with the simulated grain size. Therefore, the model is proven to be reliable. Principle stress, equivalent stress and shearing stress on the ingot were simulated based on the thermo-elasticity model. The causes of cracks were analysed by stress field simulation. In addition, the hot tearing indicator (HTI) was used to judge the crack tendency in ProCAST. The results show that the cracking tendency is greatest along the radius direction at a distance of  approximately 40 mm from the edge and in a ring shape. The crack location and shape in the simulated ingot are consistent with those in the actual ingot. Based on the third strength theory, the optimal process of semi-continuous casting of 2024 aluminum alloy with φ254 mm was explored. A casting temperature of 685~695 ℃ and a casting speed of 59~62 mm/min are the most reasonable process parameters. After test verification, 2024 aluminum alloy ingots with good surface quality and no cracks are obtained.