A stochastic model to predict radio interference fields caused by corona discharges on high voltage transmission lines has been developed. This model is based on corona discharges distributed randomly in time and space;A stochastic model for the corona current induced by corona discharges on power lines is proposed. Based on the proposed corona current model, a rigorous analysis is presented to evaluate the radio interference field caused by corona discharges on the single conductor using the stochastic method. The analysis developed for a single conductor is applied to the three phase transmission line;Most random parameters generated by the stochastic RI analysis are shown to be determined from the existing RI data.