Using a global ocean general circulation model, this study addressed the influences of different thermal and dynamical forcing fields on model simulation. We designed three different numerical experiments, including a run called Experiment W with forcing from the Ocean Model Intercomparison Project (OMIP) and the World Ocean Atlas 2009 (WOA09), a run called Experiment M in which the wind stress in Experiment W is replaced with the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) reanalysis data, and a run called Experiment N in which the thermal forcing in Experiment M is also replaced with NCEP/NCAR data. These simulations were performed with the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics (LASG/IAP) climate system ocean model (LICOM). All three numerical experiments generated the observed distribution features of water mass and large-scale circulation. A comparative analysis of these three experiments shows that because of weak wind stress in the NCEP data, the simulated circulation fields are weaker in Experiment M than those in Experiment W. The transport strength of the Antarctic Circumpolar Current in Experiment M, for example, is 13% weaker than that in Experiment W, and the strengths of two overturning cells on both sides of the equator, as well as the Deacon Cell, are reduced in Experiment M. These results reduce the transport of temperature and salinity in Experiment M, leading to increases in the differences of temperature and salinity between the simulations and observations in deep water. However, the relatively strong transport of Antarctic intermediate water in Experiment W is modified in Experiment M. Because both the short-wave radiation fluxes and other non-short-wave thermal fluxes are smaller in the NCEP data than those in the OMIP data, and the sea surface temperature (SST) in the two polar regions in the NCEP data is more than 4℃ lower than that in the WOA09 data, the simulated results from Experiment N are better, weakening the higher SST in the region south of 60°S obtained by Experiment W. Experiment N also reduced the deviation of SST in some areas of the Arctic Ocean and the eastern subtropical region that was obtained in other experiments. In addition, lower SST values in the higher regions in Experiment N enhance the transport of North Atlantic Deep Water and Antarctic Bottom Water, so that the simulated temperature and salinity in the deep water are also improved. The meridional heat transport, in the critical areas obtained by three experiments, generally lies within the uncertainty range obtained with the data-based estimate and estimates by other researchers. In general, the meridional heat transport in Experiment M is weakest. Based on the synthesis of the three simulation results, we conclude that the OMIP wind stresses and the NCEP SSTs are more suitable for use as LICOM forcing fields.