Abstract: The effect of cell seeding density on the growth of Vero cells on microcarriers was investigated. It was found that the maximal cell density obtained in the culture process increased with increasing inoculum size. However, if the surface seeding density higher than 1.0105 cells/mgMC, the cell growth was hindered to enter the exponential growth phase, due to the limitation of cell extension after attachment. The experimental results showed that the suitable cell seeding density on microcarrier surfaces was in the range of 3104 to 7104 cells/mgMC, in which the specific growth rate and the cell expansion ratio would reach high. In addition, it was indicated that the maximal cell density on microcarriers CT3 as monolayers was about 5.2105 cells/mg MC.