Abstract: In order to shorten the design of leno weave, this paper put forward a mathematic model for leno weaves. By analyzing the principle of leno weave, the threading chart can be divided into five sectors, weave diagram, leno lifting plan, common lifting plan, leno chain draft, and common chain draft. Using the matrix principle, we can abstract the weave matrix from the leno weave. According to the relationship of five sectors, we can put forward a mathematical model for leno weave. Finally we use the VB.net project system to prove the exactitude of the mathematical model. The mathematical model will be a basic theory for the CAD system of leno weave.