This paper generalized the research situation of planation surface on its definition, discrimination, classification, formation, dating, and so on. We think that planation is a wide-ranging and undulating surface formed by deplanation in a long and relatively stable period. Planation is always be uplifted by the later tectonic activities. Planation has such features as large area,low altitude and small gradient. Discrimination of planation is based on inside plotting and outside investigation. This method mainly depends on subjective knowledge which is lack of accurate,objective and quantitative analysis.New mathematical methods have been used in this field.Although they are not accurate yet,there are still many improvements. There are lots of ways to classify planation in terms of different standards.The same planation may show different type when it is in different system.The same planation even has distinct forms at different places. We strengthen the investigation of natural factors such as pre-construction,erosion base level,climate,lithology,time and tectonic activities, which affect planation's formation and preservation. Pre-construction provides a foundation for planation forming.Erosion base level is the base line for it.Climate and lithology influence the rate of formation and preservation.Time produces different degrees of planation forms.Tectonic activities are unbenefical to preservation. Chronology of planation's forming is one of the most important part of the study.It means the end of the deplanation.Phase-transition analysis,age-boundary line analysis,correlation and crust of weathering analysis are all used in determing the age of planation. We also disscuss the perspective researching trends on the study of planation surface.