Shear dilation is one of the important characteristics of geomaterials. Rowe’s dilatancy equation is of a classic type

which reflects the dilatancy of coarse-grained soil

rock

and even concrete

featuring a simple form and fewer assumptions. It is widely acknowledged in the world and has been improved and developed by many researchers. However

some concepts in the previous derivation of this equation need to be discussed

and its separation planes of a tooth shape may mislead the readers. In this paper

the equation and its improvements and developments are reviewed

and a new derivation method using the concept of a reference plane is presented. It is thought that the new derivation is more rigorous in concept

and the investigation of these two methods sheds some light on our understanding of Rowe’s dilatancy equation.