Abstract: By using the physical quantity parameters of Yibin sounding at 08:00 and 20:00 from December 1, 2019 to December 31, 2020, the practicability of the potential forecast index and radar warning index of Yibin hail are evaluated comprehensively, it is applied to a hail process on the night of May 4, 2020. The results show that: The sounding potential forecast at 08:00 on May 4 had certain guidance significance in the early preparation of hail prevention work. No hail was forecasted at 20:00, but there was great possibility of strong convective hail weather at night, so the deviation between the sounding potential forecast and the actual situation did exist. The radar warning index gave sufficient guidance to the two hails at 23:30 on May 4 and 01:15 on May 5, and hails appeared within 5 minutes of the warning index. In general, the sounding potential forecast and radar early warning index had certain guidance significance, but they had certain deviations, so further refinement was needed.