A model combining air and sea interactions was used to study summer rainfall in eastern China. The coupled model showed better simulation of rainfall patterns compared to the uncoupled model. It accurately represented the distribution and intensity of rain in North and South China. The model also matched observed rainfall data well from 1985 to 2004. By improving the simulation of sea surface heat flux, the model better captured the monsoon circulation and water vapor transport, leading to improved rainfall predictions in eastern China.