The 1280×1024 infrared focal plane detector is taken as an example, and 3D visualization entity simulation software is used to establish a 3D model including cold finger parts, ceramic frame and detector chip in this paper. The simulation comparison is conducted by using ANSYS simulation software (only the spherical cold platform structure is different from the conventional cold platform, and other parts are the same). The results show that the spherical cold platform can achieve lower thermal stress and smaller thermal deformation of the chip by increasing the area of the contact surface between the cold platform and the refrigerator. And the reliability of the detector chip can be improved by this way.