In the course of studying the image quality assessment of photoelectric measurement equipment, the influence approach of the high frequency component of image spectrum to image quality subjective evaluation of the human eye and solving measures are analyzed. The clear image is processed by Butterworth low-pass filter in frequency domain. Then the influence of the high frequency part of image spectrum to the human eye subjective feeling is analyzed by filtering the image. The modulation transfer function (MTF) of defocus imaging system is measured by using the canted slit method, and the corresponding defocus blurred images are evaluated subjectively. Spectrum analysis and image evaluation of images acquired by the cameras with different pixel sizes are carried out. Experimental results indicate that the images have more high frequency component, richer details and higher clarity. Focusing exactly and capturing by camera with small pixel size are important measures to improve the image quality of the photoelectric measurement equipment. Other influencing factors and improving methods are proposed and the improving measures are put forward.