Inactivation and reactivation of photosynthetic oxygen evolving complex were studied with isolated spinach (Spinacia oleraceda. L.) photosystem Ⅱ particles by the activity of oxygen evolution and chlorophyll fluorescence. When the particles were treated with Tris and urea, the oxygen evolution was inactivated and three polypeptides having molecular weights of 33 kDa, 24 kDa and 18 kDa were simultaneously released. But in NaCl-treated particles, two polypeptides of 24 kDa and 18 kDa were removed from PS Ⅱ particles. The oxygen evolution activities of Tris and urea-treated particles were not restored by adding cation ions (Mg^2+, Mn^2+ and Ca^2+), but the NaCl-treated particles were restored by exogenously added Ca^2+. The removal of these extrinsic polypeptides, especially 33 kDa, markedly showed the decrease of the variable fluorescene (Fv). These results are likely to be due to dissipate thermal energy by antenna of photosystem Ⅱ complexes.