Based on the data of precipitation in spring from 1995 to 2001 in Henan, a new method was developed combining numerical prediction and statistical analysis techniques to evaluate the effectiveness of precipitation enhancement by airplane seeding. The basic idea is that the numerical forecasts for historical raining processes were formulated and a series of precipitation forecasts were obtained in terms of the MM5 V3 numerical model in the same evaluation area, which was partitioned based on the climatic rainfall characteristics. The statistical equations between precipitation forecasts for non-seeding precipitation processes and observed precipitation were established. The rainfall of the seeded precipitation processes was predicted with the above model and compared with the observation. The effectiveness of precipitation enhancement was finally gained. The results show that the average effectiveness of precipitation enhancement in spring from 1995 to 2001 is 16.7% in the northern Henan and 19.3% in the eastern Henan, respectively.