Slope classification is an important precondition for slope mapping.It divides slope classification methods into three kinds: commonly subjective classification methods,critical classification methods and mode classification methods.It takes a gully and hill area of loess plateau as the test area and regards DEMs of 5 m resolution as the information source in the experiment.Slope gradient layer can be created the first.Then more works is done to make a comprehensive comparison on the characteristics,applicability and mapping effect of different classification methods.Study shows that commonly subjective classification methods are simple and flexible,but classification results have some randomicity and subjectivity,and often depend on users' professional level and experience.Critical classification methods can satisfy users' application aims well,but mapping effect are often ignored.Mode classification methods may discover the rule of real relief.The three kinds of slope classification methods have different characteristics and applicability,we should choose proper classification methods based on application aims and characteristics of slope data.The result in this research should be of significant values in directing correct and effective applications.