Abstract: In order to study the non-contact measurement method for slope angle in open-pit mine, we proposed the limitations of traditional measurement method, and deduced calculation formula for whole slope angle, as well as the bench slope angle. Based on control variant method, we analyzed parameters which influence the measurement result and its reliability. The results illustrate that different parameters' errors show respective impact extent on the measurement result, they all follow a linear relationship with the result error. And among these parameters,α_i presents obvious influence on the result while α_i-1 does the smallest. Consequently, during the non-contact measurement process,α_i error should be limited to ensure the accuracy of the measurement results.