Under the same experimental conditions, exogenous Ca2+ had no effect on the proliferation of S. cerevisiae, but it could obviously stimulate the proliferation of S. pombe. Ca2+ chelator EGTA had no inhibition effect on the proliferation of S. cerevisiae, but it apparently inhibited the proliferation of S. pombe and the inhibition could be effectively overcome by adding Ca2+. Non-special ion chelator EDTA could inhibit the proliferation of both S. cerevisiae and S. pombe, but the inhibition could not be overcome by adding Ca2+. The results above directly showed that the dependence of the proliferation of the two kinds of yeast on exogeneous Ca2+ was different. The growth rate of S. cerevisiae was about 3 times that of S. pombe and the proliferation of S. cerevisiae was independent on the exogenous Ca2+, which was similar to transformed cells. Therefore, in order to understand the relationship between the disorder of cell cycle and cell transformation, it was very important to study the mechanism of different effects of exogenous Ca2+ on the proliferation of the two kinds of yeast.