Abstract: In order to decrease the probability of sliping and falling accidents, effect of environmental factors on step friction coefficient was studied by Mark II slip meter, using common step friction couple materials as samples and several work conditions as test conditions. The result shows that all the factors including materials of friction couple, test conditions and interactions between two factors affect step friction coefficient. Of all the factors, effect of test conditions is most significant. Friction coefficient of dry condition is highest and that of oil condition is lowest and it approches to zero. Friction coefficients of lubrication conditions except for oil condition have no significant difference. The interactions between two factors indicates that friction coefficients of upper and lower samples keep the same trend when test condition is constant but this trend changes with test condition. The variation of friction coefficients is attributed to the surface feature of materials and the lubrication effect of liquids.