Abstract: A fast CCD camera image acquisition system for EAST was introduced in this paper. According to the characteristics of plasma image position during the plasma discharge, an improved active contour model algorithm was proposed in real-time plasma boundary detection. By using least squares method to fit the edge of plasma, the center and the radius of the plasma edge were obtained. It has considerably practical meaning for further control of plasma. The experiment results during EAST discharge show that the method presented in this paper can realize the expected goals and produce almost perfect effect.