In this paper,ergonomics is taken as the guide to design and study the single soldier photoelectric handheld devices,which aiming to improve the man-machine performance of such devices and strengthen the application of ergonomics in the design.Through the man-machine data relation,man-machine interface design,shape design,color and material analysis,the specific and effective design principles are put forward； the handheld thermal imager is designed and optimized.The application of ergonomics can effectively optimize the man-machine relationship,make the equipment safe and comfortable,easy to operate,so as to improve the user experience.