Abstract: Aiming at the extensive application of the active laser detecting based on cat-s-eye effect in electro-optic counterreconnaissance, we built the mathematic model of the optic-echo index for the head-on sight electro-optic equipment and the mathematic model for detecting range combined with the detecting components, simulated the numerical value relation between the optic-echo index and the internal characteristic parameter, and the one between the detecting range and the primary parameter for the head-on sight electro-optic equipment- In order to verify the mathematic model-s correctness，taking the 2.5 mm,5.5 mm aperture cat-s-eye retroreflectors and the 25 mm,35 mm,56 mm aperture sight electro-optic equipments as the targets, and the active laser detection equipment as the detecting system, we conducted maximum detecting distance simulation and verification tests, the analogue detecting ranges were 1 290 m,1 656 m, 866 m, 1 919 m and 1 266 m, respectively, the maximal detecting ranges were 1 100 m,1 500 m, 800 m, 1 800 m and 1 200 m, respectively. The result demonstrates that the analog numerical values are accordant with the test numerical values for the maximal detecting ranges.