Abstract: The suspension roselle cell was used to study the effects of inoculum amount and sucrose concentration on its growth. The results were as follows: the bigger the inoculum amount was, the faster the roselle cell started to grow, but the smaller the specific growth rate was. From these facts, the density dependent of cell starting to grow and density inhibited of cell growth were proposed; Sucrose was limiting substrate from 2% to 4%; But from 4% to higher concentration, the sucrose showed inhibition effect on cell growth. The dual effects of sucrose on cell growth were apparently seen from the utilization of nutrients ,such as sugar and nitrate.