Abstract: A new form of graphic generator based on an algorithm named "plus-minus method" is described in this paper, This graphic generator is designed to generate all kinds of 2-D curves described by linear, quadratic and cubic polynomial equations but without cross-pro-duct terms. The equation coefficients of the given curve segment are directly used as input data in the suggested graphic generator. Its output is a sequence of stepping control pulses available for general use. In this paper the al, gorithm, circuit structure and the function of this graphic generator are discussed. And practical tests have shown that the performance is quite satisfactory.