AC corona discharge characteristics and radio interference (RI) performances are studied by using a small corona cage with different applied AC voltages. Characteristic parameters of AC corona pulses are analyzed statistically, such as average amplitude and repetition frequency. Besides, RI levels generated by corona pulses are measured simultaneously. Then the relationship between current pulses and RI levels are discussed. It is found that, the measured quasi-peak RI current value lies between the peak and root-mean-square (RMS) current value calculated from the measured corona current pulse by using the frequency processing method, and there is an approximate linear relationship between RI level and product of positive pulses amplitude and square root of positive pulses frequency.