In order to meet the requirement of equipment maintenance support in low illumination condition at night, a visible/near infrared achromatic objective lens with large relative aperture is designed. The secondary spectrum can be well corrected in the visible/near infrared band by mean of selecting suitable optical glass materials. The designed large relative aperture objective lens has a focal length of 3.75 mm, F# of 1.2, field of view of 70.25°, distortion of -17.5% and a total length of 40 mm. The con-focal objective lens can meet the requirements of night observation without focusing in the spectral range of 486~950 nm, which provides a new technical means for the development of optical module of low-illumination night vision head-mounted system.