In the paper, the three-coupled-oscillator model presented by us is used to study the optical rectification in isotropic chiral films. The zero frequency hyperpolarizabilities of chiral molecules with a tripod-like structure are calculated. The expressions of the static-electric polarization and the relations between the optical rectification and the microscopic parameters of chiral medium are. obtained by theoretical derivation. Furthermore, the relations of the dc electric-dipole polarization with the wavelength of incident light and microscopic parameters of chiral molecules have been simulated numerically.