This paper evaluates the relationship between rainfall and sea surface temperature (thereafter SST) simulated by the new version of LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences) climate system model (FGOALS_s), which takes the recently improved version of spectral AGCM (SAMIL) as its atmospheric component. To understand the impacts of air－sea coupling on the simulation of relationship between rainfall and SST, results from FGOALS_s and AMIP-type simulations with SAMIL are compared. Since observational results show that rainfall anomalies are mainly forced by SST in the eastern equatorial Pacific and oceanic forcing from FGOALS_s is weaker than that from the observation, SAMIL has a better performance in simulating the relationship between rainfall and SST in the eastern equatorial Pacific. On the other hand, in summer and autumn, the SST anomalies in the western North Pacific are mainly induced by atmospheric forcing, so coupled model FGOALS_s can properly capture the nature of relationship between rainfall and SST because the air－sea coupling processes are included. Bias related to convection parameterization used in SAMIL leads to an increased surface downward shortwave radiation flux while rainfall increases in the eastern equatorial Pacific during September to November. To some extent, this discrepancy maintains after coupling. So it is urgent to improve the convection parameterization in the AGCM. Besides, it is found that the latent heat flux overly depends on the air－sea moisture differences in the coupled model.