Abstract: In order to extract the layer for space-borne cloud/aerosol lidar reliably, a layer classification method based on histogram statistics was proposed. This method was analyzed theoretically. The experimental results show that the cloud/aerosol layer can be extracted reliably in different situations with this method. Compared with the current layer detection method, the new method can avoid the constraint for data feature. It is a highly-reliable and widely-applicable layer detection method.