This paper analyses barotropic vorticity,barotropic enstrophy,baroclinic vorticity and baroclinic enstrophy of the blocking in Okhotsk in 1998 by the use of barotropic and baroclinic decomposition.The results are as the follows:At the different stages of blocking,barotropic vorticity and enstrophy are far more than baroclinic vorticity and enstrophy,and both have different evolutional feature.At the developing stage,vorticity and enstrophy(including barotropic and baroclinic) increase instably and spread southwestward.At the maintaining stage,vorticity and enstrophy of barotropic and baroclinic reach maximum when blocking has built and stayed at the blocking field.At the decaying stage barotropic vorticity and enstrophy and baroclinic vorticity and enstrophy decrease instably and spread southeastward and the blocking disppeared.