Hail suppression operations were carried out in Mancheng county from 1986-1990. Hail damage area was 2193 ha (10 year average) befroe the operations. In the period of hail suppression the damage area was decreased to 633.3 ha, much less than before. The effects of hail suppression was estimated by two ways. The results suggested that the effect of 5 year hail suppression is 77.6%,the operation is beneficial and the ratio of investment to benefit is 1:17.6 or 1:23.