Abstract: Objective To study the method of the detection of microbial cell by a voltammetric Biosensor.Method An electro-chemical method for detection of microbial cells was developed by appling semi-differential cyclic voltammetry to microbial cells.A modified basal plane pyrolytic graphite electrod was empolyed as a working electrod.Applying a sweep voltage between a working electrod and a counter electrod while the microbial cells on a membrane filter were brought into contact with the working electrod.Then measure the gener ated cur rent between the electrodes in phosphate buffered soline.Results The anodic peak potential of S.cerevisiae was 0.75V(vs Ag/AgCl electrod).The relationship between the peak current and the cell concentration of S.Cerevisiae was studied.The anodic peak current was proportional to the cell numbers on the membrane filter in a range of(0.5-2.5)×10⁷ cells.Regression equation Y=0166+0.56X(×10⁷ ),correlation coefficient 0.9901.The minimum detectable cell number was 2.8×10⁶ cells.Conclusion Cell numbers of microbial cells could be determined from the anodic peak current of semi-differential cyclic voltammetry.