Investigation of photosynthetic activity of Picea abies was carried out in the Moravskoslezske Beskydy Mts to identify vertical distribution and differences of photosynthetic activity within canopy of two stands with different silvicultural activity. The stand structure has a large influence on radiation conditions within the stand canopy and on differentiation of photosynthetic activity (PA). Vertical distribution of PA divides the stand canopy into three different crown layers. There are significant differences between PA of the lower crown layers and the upper ones. Thinning is responsible for differences in the portion of the lower crown layer in the whole canopy photosynthetic activity. Thus the effect of thinning was documented on an increase in PA portion of the lower crown layer on the whole canopy PA in comparison to control (unthinned) stand.