The work aims to study the effect law of the content and size of SiC particles in Ni-based composite electroplating coating on the top surface of automobile engine piston on the thermal stress at the piston-electroplating coating interface. The two-dimensional finite element model of the piston with SiC particles reinforced Ni-based composite electroplating coating on the top surface was established by ABAQUS software and python language. Combined with the relevant theories of heat transfer and thermo-elasticity and the actual service conditions of the piston, the heat exchange boundary conditions and the load value on the top surface of the piston were determined. The effects of SiC particle content and size on the interfacial stress between coating and piston under the combined action of heat and airborne load were systematically studied by the sequential thermal mechanical coupling finite element analysis. According to the finite element simulation results, when the top surface of the piston was subject to high temperature and high pressure, the content of SiC particles was one of the factors that significantly affected the equivalent stress at the coating-matrix interface. The peak equivalent stress at the coating-piston interface increased with the increase of the particle content in the range of 1vol.%-15vol.%, rising from 437.08 MPa to 472.98 MPa. The size of SiC particle was a secondary factor affecting the coupling thermal stress at the coating-matrix interface. When the SiC particle size was in the range of 0.3-1 μm, the peak equivalent stress at the coating-piston interface remained unchanged, which was about 437 MPa. Considering the performance requirements of the composite electroplating coating on the top surface of the piston and the relationship between the stress at the coating-piston interface and the bonding property and combined with the actual electroplating process, it is determined that the volume fraction of SiC particles in Ni?SiC composite electroplating coating is about 10% and the diameter of SiC particles is about 0.4-0.8 μm.