Abstract: Using ab initio method of GAMESS program, we calculate and analyse the changes of molecular geometry and electron structure of cholesterol molecule in the cell membrane under the high electric field,and compare the results with those under the E=0. The results illustrate that molecular geometry becomes somewhat different,but electron structures change a little. These results provide strong supports for the microscopic theoretical study of bio-molecule under the inherent high electric field(produced by resting potential) of the cell membrane.