The global SSTA for past 136years(1856-1991)was studied with singular spectrum analysis,then a maximum entropy spectrum analysis for serveral principal components was conducted.The result shows that SSTA has serveral very evident periods of quasidecade and 26-6 years besides 81 years.The first fifteen principal components have a variance contribution of 78%.Eigenvector 1,2 stand for linear characteristic of SSAT,their variance contribution is 48%,and their resultant curve basically described average thenes during serveral years and serveral decades.Eigenvector 3 and afterwards eigenvectors stand for wave characteristics of SSTA.The first four principal components can better fit SSTA yearly change characters.