With the continuous development of refined forecast, we urgently need to construct the data environment to support the nationwide refined forecast system, which implements the function of realtime synchronization and concurrent gridded weather prediction between national and provincial levels. This paper analyzes the features of refined forecast and introduces the system architecture, data flow, core functions and technological realization of the data environment, which is based on the China Integrated Meteorological Information Sharing System (CIMISS) and designed to support the refined forecast system. Via the operational application it can be concluded that the data environment successfully completes the target of realtime synchronization and sharing of the gridded weather prediction products between national and provincial levels, provides sufficient capacity to support the correction and publication of the products, and ensures the products’consistency. Finally, this paper looks into the advancement of the data environment to support the nationwide refined forecast system in the future.