In order to express the pitch curve of non-circular gear conveniently in a uniform way, which would lessen the complexity of calculating the tooth profile of non-circular gear, the authors propose a curve fitting method of NURBS curve with the least data points based on the fitting of NURBS curve. This method is used to express the pitch curve of non-circular gear, and the specific solution model and detailed calculation procedure are presented. In addition, a method to select data points inhomogeneously and appropriately using non-uniform factor of selecting points is proposed. Two design examples are introduced to testify the validity of this expression method. © (2012) Trans Tech Publications.