In order to meet the space application requirements of the large format Mosaic infrared detector, ultra-scale cold platform need to work at low temperatures, and the cold platform support structure requires high rigidity to meet the components' anti-vibration performance, and a high structure thermal resistance to reduce its conduction heat leakage. A symmetrical eight-bar structure is proposed as the cold platform support, which adopts a new type of zirconia ceramic material with high strength and low thermal conductivity. Based on the finite element software, the influence of the height of the support structure, the installation inclination angle, the aspect ratio and the material on the modal fundamental frequency of the module, the thermal resistance of the support structure and the maximum stress of the module under 30 g static load are analyzed. A set of parameters is used to design the actual test component, the thermal resistance of the support structure reaches 220 K/W, and the components are subjected to a 5-2 000 Hz sine frequency sweep test, a total root mean square of 9 g RMS, and random vibration in the three directions of XYZ and other mechanics. In the environmental test, the final component passes the experimental verification of space environment adaptability. The fundamental frequency of the component reaches 560 Hz, and the test results are in good agreement with the simulation results. The results show that the symmetrical eight-rod zirconia support structure solves the problem that the cold platform of the large format infrared detector requires both high mechanical properties and low heat leakage, and meets the needs of engineering applications.