This letter proposes a computationally efficient sequential estimation of integer carrier frequency offset (IFO) and sidelink identity (SID) in the long term evolution-device-to-device system. To detect the IFO without a priori knowledge on the SID information, the proposed detection method utilizes the conjugate property between two primary sidelink synchronization sequences. This design facilitates joint detection of the IFO and SID so that it can be detected sequentially. Simulation results indicate that the proposed sequential detection scheme has good performance and reduces computational complexity significantly compared to existing detection methods.