The 286 grid data of monthly mean SST from 1949 to 1987 in North Pacific are analysed by the prinicipal component analysis.Based on the analysis, there are twelve patterns of annual variation of the North Pacific SST. This paper gives a disussion on characteristics of the first three annual variation patterns which account for 95 percent of the total variance.Contributive percentages of these first three patterns at each grid point are also calculated respectively.Thus the North Pacific SST cans be divided into eight regions, as a result of inspecting the special distribution of the percentages.Finally, the different SST statistical feature within each region has been explained.