Based on the 533 year dryness and wetness grades series, the Moving Cumulative Frequency Method (MCFM) was developed, and a moving average precipitation field series from 1499 to 2002 was reconstructed. The results show that there is good relationship between the reconstructed series and the primitive 49 year observation precipitation series, their relative root mean square errors are below 1 89%; and the reconstructed series has a nonlinear relation to the dryness and wetness grades series. It means that the reconstructed series is reliable. The reconstruction of the moving average precipitation field series laid a foundation for researching the regularities of drought and flood evolution.