The time synchronization accuracy on the order of nanoseconds can be provided using the conventional methods of time synchronization, a higher measurement accuracy on the order of femto-seconds can be reached by quantum measurement which employs entangled photon pairs in order to break the limit of measurement accuracy of conventional methods. The second-order correlation function of the entangled photon pairs which produced in a spontaneous type-Ⅱ parametric down-conversion is investigated by integral transforming in the nonlinear crystal and substituting the first order expand of the wave vector. The relation between the second-order correlation function and temporal difference. A quantum method in clock synchronization between satellite and ground station is proposed based on the temporal correlation. The simulation indicates that the measurement accuracy provided by the second-order correlation function can be 70 femto-seconds and the synchronization accuracy in the scheme can be 140 femto-seconds in the ideal case.