The coefficient of friction is an important parameter for the characterization of optical glass polishing properties. The average coefficient of friction determines the polishing rate, and its variation range affects the surface accuracy and surface roughness of optical glass. In this work, the orthogonal experiments are designed to study the influence of the experimental parameters on the friction properties between phosphate laser glass and optical polishing pitch in the polishing process. The degree that experimental parameters influence the average value and variation range of coefficient of friction is similar. The influence of the applied load is larger while that of polishing pitch type is smaller. A large average frictions coefficient corresponds to a large variation range of frictions coefficient in the experiment. Furthermore, the reasons for the change of frictions coefficient with time are discussed from the aspects of stick-slip friction, adhesion, abrasive grinding and polishing liquid thickness.