To address the stringent requirements for sensitivity and signal to noise ratio (SNR) of infrared imaging systems in weak target/background multispectral characteristic measurements,an overall design scheme for a high sensitivity infrared multispectral camera based on cryogenic optical technology is proposed in this paper.A physical model of optomechanical background radiation is established,stray light suppression measures are optimized,and optomechanical radiation simulation analyses for each infrared band are completed.The simulation results show that the total illuminance of optomechanical radiation on the image plane ranges from1.50×10 -2W/m2 to 1.79×10 -2W/m2.Through radiation calibration tests in a simulated vacuum environment,the accuracy of the simulation results is verified,with a maximum deviation of 2.78% (in the B4 spectral band).The error between the simulation results and experimental data is within 3%,confirming the precision of the optomechanical radiation simulation method.This study provides important references for the design and optomechanical radiation analysis of cryogenic high sensitivity infrared multispectral cameras.