A case on April 18, 2009 in North China with the complex of stratiform clouds and embedded convective clouds is simulated by using WRFARW model. First, we analyze synoptic chart, radar reflectivity image and vertical section of radar reflectivity. Second, by comparison, it shows that the simulation results of precipitation and radar reflectivity are nearly correspondent with observational data. The precipitation mechanism, cloud microphysical characteristics and dynamic characteristics are studied by analyzing elements of cloud. The results indicate that: liquid water content of the stratiform clouds and embedded convective clouds is inhomogeneous. The stratiform clouds and convective clouds connect each other, and mix horizontally. The locations of maxima of rain water, ice crystal and cloud water content are correspondent vertically. Seederfeeder mechanism is obvious. Vertical velocity is accessional in the convective clouds. Downdraft is on the side of the convective clouds at high altitudes. Convergence can be found at low altitudes, while divergence can be found at high altitudes. This configuration is conducive to maintaining the development of cloud.