The real-time visualization system of plasma shape is developed for studying the divertor plasma in HL-2A. The plasma boundary reconstruction code CF(Current Filaments) are written using the current filaments model and the finit current element model. The information of the magnetic field around plasma is collected with USB data acquisition card UA301, having 100kHz/s, 32 channels with simultaneous sampling. A compatible computer with 3GHz E CPU processes the data. This system collects and stores data in every 4ms, and plots the plasma boundary in every 16ms. After discharge, the mgnetic field at the plasma boundary and some plasma parameters which are deduced from it are calculated.