According to the problem that stray radiation exists in the process of imaging at shortwave infrared lens. The stray radiation analysis and suppresses research of lens are carried on. By imaging experiment, the stray radiation phenomena of lens is analyzed preliminarily. The analysis model of shortwave infrared lens is established using simulation software Tracepro, the point source transmittance (PST) of system is obtained, rays tracing is conducted according to the experimental phenomenon, and the possible path of stray radiation is found out. Stray radiation is restrained by increase lens hood, modify the structure and adding extinction stray light coatings. The measured PST after taking the proposed methods can prove the effectiveness and trustiness of these methods, and reach the goal of suppress stray radiation of the lens and improve image quality.