To counter the problem of cracks which are easily occurred in the horizontal sliding door lock head during construction,we try to exert prestress to the gate chamber.Combining Fortran language and ANSYS finite element analysis software,we analyze the process of pouring and get the stress distribution at the loch chamber,and carry out comparative analysis of the temperature stress before and after exertion of the stress.The result reveals that after exerting the prestress,the maximum tensile stress at the loch chamber decreases from 1.98 MPa to 1.80 MPa,which is lower than the control standard of concrete stress.It verifies that the method of prestress is feasible for preventing and curing the crack of the gate chamber.