Firstly, the basic principles infrared radiation characteristic measure was presented. Due to the diffraction effect of the optical system, point target’s image is a dispersed spot. Point target radiation characteristic measurement accuracy is generally very low. View of this situation, one point target radiation characteristic measurement optimization algorithm based on radiation energy conservation was proposed, Specific principles and implementation process was given. Finally, point target radiation characteristic measurement experiment was done, and the results were analyzed. The results show that the point target radiation measurement optimization algorithm’s accuracy is better than 10%, indicating that the point target radiation characteristic measurement optimization algorithm has large application prospects in practice.