In this paper, the data of the historical (cmip6) experiment of the earth system :model CAS-ESM 1.0 are used，which are 84 years in total from 1922 to 2005. Combined complex Empirical Orthogonal Function (CEOF) analysis is applied to the upper circulation anomalies in the tropical Pacific Ocean in January, and the simulation results are compared with the SODA (Simple Ocean Data Assimilation) data to examine the simulation ability of the model for the upper equatorial ocean flow field. The main conclusions are as follows: The variance contribution of the first three modes of the CEOF decomposition are 53.5%, 12.9% and 9.5%, respectively. The cumulative variance contribution is 75.9 %, which is higher than the SODA data. The first and second eigenvector pattern is generally similar to that of the SODA data. The anomalous flow fields are captured by the equator, which are dominated by the partial latitudinal flow in the capture region. The difference is that the equatorial capture area in this paper is larger than that of the SODA data, and the longitudinal flow component and the cross-equatorial flow are also more obvious. There is no linear trend in the real time coefficient sequence of the first and second modes in this paper, but there is this trend of the SODA data. The inter-annual variation of CEOF modes is the similar to that of the SODA data. The inter-annual variation of 3-5 years in the first and second mode is a reflection of ENSO (El Ni?o-Southern Oscillation). The inter-decadal variations of the first and second modes are not obvious. The dynamic temperature anomalies of the first and second modes in the subsurface layer of equatorial Pacific Ocean show the distribution of dipole and three-pole respectively, and corresponding to Sea Temperature Anomaly of the eastern and central ENSO. The first and second modes can be called the eastern and central ENSO modes. The asymmetry of ENSO is obvious in the first mode and accords with the real situation. The earth system model performs well in simulating the upper flow field of the tropical Pacific Ocean.