The design of fulcrum line is determined by the position of occlusal support (exactly, by the type of missing). Generally speaking, it can be divided into four types: diagonal type, horizontal type, vertical type and plane type. In this paper, dentition loss is divided into three types, which are designed as 5 1 distal occlusal support, 7 1 mesial occlusal support removable partial denture and two kinds of occlusal support attachment. Test site: fulcrum line knowledge