Abstract: A regional four-dimensional intermittent data assimilation scheme has been developed by using the analysis scheme, initialization scheme and model scheme of limited area analysis and forecast system (LAFS) in NMC in China. Some forecast experiments of heavy rains in China in 1992 are made by using the assimilation scheme. The experiment results show that the skill of forecast both weather system and rainfall from the assimilation initial values, especially from those of fine-mesh scheme, is much better than the skill of control forecast based on LAFS scheme.