Based on the Coupled Model Inter-comparison Project (CMIP5) coordinated experiments results simulated by the IAP Flexible Global Ocean-Atmosphere-Land System Model (FGOALS), the temporal and spatial variation characteristics of the East Asian Subtropical Westerly Jet (EASWJ) could be well captured. In particular, the land and sea patterns of the EASWJ divided by the borderline of 120°E were also well reproduced. Compared with the NCEP/NCAR reanalysis data, some biases in the intensity and position of the EASWJ simulated by the FGOALS model during the Meiyu period were found. FGOALS could reproduce the characteristic morphological changes in the EASWJ over the Northwest Pacific during the period of ENSO evolution, but the simulated intensity and characteristic eastward extension of the EASWJ in El Niño years and its westward shrinkage in La Niña">La Niña years were different to that of observations. According to the thermal wind principle, geostrophic wind relationship and wave activity flux, and so on, possible reasons for the simulated biases were investigated. The simulated Tibetan Plateau heating effect decreased and the convection in the low latitudes weakened, which led to decreases in ascending motion in the middle and upper troposphere and less latent heating. As a result, anomalously cooling occurred at the middle and upper troposphere and the South Asia High (SAH) weakened. The meridional temperature gradient, the pressure gradient force on the northern side of the SAH, and the atmospheric internal dynamic effects all became anomalously weak, resulting in the deviation of the intensity and location of the EASWJ. The position and intensity of the EASWJ during the Meiyu period are closely associated with the spatial distribution and intensity of heavy precipitation in the middle and lower reaches of the Yangtze River. The position of the simulated EASWJ was obviously more northward and westward and its intensity was weaker than observation. This explained why the simulated Meiyu precipitation amount became less, especially in the lower reaches of the Yangtze River. In addition, the atmospheric circulation anomalies simulated by the FGOALS model in the years of ENSO need to be improved.