To meet the requirement of wear eye protection and gas mask when using the military sighting telescope, the exit pupil distance of eyepiece is needed to be longer than the other. The optical characteristics and aberration characteristics of eyepiece with long exit pupil distance were analyzed, and the configuration of positive, positive, and negative three lens groups was proposed. According to the aberration theory, the optical power distribution formula was derived by analytical method. The eyepiece with long exit pupil distance was designed with optical design software ZEMAX, the focal length was 20 mm, exit pupil diameter was 5 mm, view angle was 40°, exit pupil distance was 40 mm, and relative eye clearance was 2. Designing results show that the MTF of every field above 0.2 in 40 lp/mm satisfy the application requirements of visual optical instrument.LI Li，WANG Xingbin，ZHANG Weiguo. A recognition method of “Cat-eye” effect target based on texture character [J]. Acta Photonica Sinica，2014，43(2)：0210001-1-0210001-11.