The formulation and justification of a three-layer baroclinic ocean model developed to simulate thegeneral circulation of the ocean are described in this paper.Test of the model in simulating the annualmean circulation patterns in the North Pacific under the prescribed atmospheric forcing,which consists ofthe climatological surface wind stress and sea surface heat flux,and comparison of the results withobservations showed that the model basically simulated the large scale features of the annual meancirculation patterns in the North Pacific Ocean such as those of the intensified western boundary currentsand the North Equatorial Currents and Undercurrents.But due to the coarse resolution of the model,some details of these currents were poorly reproduced.The seasonal variations of the North Pacific Oceancirculation driven by the seasonal mean sea surface wind stress was calculated,the different aspects of theseresults were analyzed and the main current(the intensified western boundary currents)transports we The formulation and justification of a three-layer baroclinic ocean model developed to simulate the general circulation of the ocean are described in this paper. Test of the model in simulating the annualmean circulation pattern in the North Pacific under the prescribed atmospheric forcing, which consists of the climatological surface wind stress and sea surface heat flux, and comparison of the results withobservations showed that the model substantially simulated the large scale features of the annual meancirculation patterns in the North Pacific Ocean such as those of the intensified western boundary currents and the North Equatorial Currents and Undercurrents .But due to the coarse resolution of the model, some details of these currents were poorly reproduced. The seasonal variations of the North Pacific Oceancirculation driven by the seasonal mean sea surface wind stress was calculated, the different aspects of these results were analyzed and the main current (the intensified western boundary cur rents) transports we