In this paper is presented an analysis of the mechanical effect of horizontal rotating bioreactor on cell culture. Getting the microgravity of the bioreactor and the shear stress on canine mesenchymal stem cells (cMSCs) with theoretic calculating model and differential equations, we have validated the density,growth rate and modality of cultured cell by scanning electron microscopy. The horizontal rotating bioreactor which we developed could create the mechanic environment of microgravity (K<8.38 X 10(-2))and low shear stress(r<1.62 dyn/cm2) in theory. The results of scanning electron microscopy indicated that the cells' growth-speed, quantity and modality in bioreactor were better than those of cells cultured in static 24-well plate. The mechanical environment of the rotating bioreactor is propitious for keeping better modality and more rapid proliferation of cMSCs. The rotating bioreactor is a novel approach and technique it is superior to static culture.