Abstract: Using barotropic and baroclinic enstrophy equations, an Okhotsk blocking occurring from June 3—11, 1998 is diagnosed. Results show that total enstrophy and the barotropic counterpart vary remarkably, clearly revealing different characteristics in fermenting, maintaining and decaying phases of the blocking, and barotropic and baroclinic kinetic energy shows insignificant features for the blocking development. The inter-transformation of the barotropic and baroclinic enstrophy and their flux generating mechanism in and outside the blocking region are two major factors for its establishment and maintenance, which occurs in such a way that baroclinic enstrophy is made to grow through the net flux mechanism, followed by converting increased baroclinic enstrophy via the mechanism into barotropic enstrophy and through their transformation mechanism the increased barotropic is converted into baroclinic enstrophy; at the same time barotropic entrophy is made to increase via its net flux generating mechanism. The combination of the two mechanisms causes barotropic enstrophy increase and remain constant, leading to the formation of the blocking circulation but, in contrast, baroclinic enstrophy increases very little.