[Objective] A variety of slope classification methods was applied for slope mapping to explore the influence of different methods on them.[Methods] We selected three sites that are in Suide County of Shaanxi Province, Qinling Mountains in Meixian County of Shaanxi Province and Baiquan County of Heilongjiang Province as the case study areas. A variety of slope classification methods were applied to classify slope. Using the quantitative indicators, we analyzed the spatial pattern and statistical distribution characteristics of slope map.[Results] (1) For specific site mapping, quantile or Evans classification method is better; while for comparison of different sites, unified classification scheme is better; (2) Spatial variation decreased dramatically after slope was classified; (3) All slope classification methods lose some slope information; (4) All slope classification schemes were difficult to represent statistical distribution law of slope accurately.[Conclusion] (1) The slope surface and natural breakpoint methods are better; (2) With the increase of grading space, slope information declines rapidly in a power function; (3) Statistical distribution of slope is better to be mapped with slope surface and natural breakpoint methods.