A method of detecting a synchronization signal at a device-to-device (D2D) user equipment (UE) in a wireless communication system includes receiving a primary sidelink synchronization signal (PSSS), determining a normalized carrier frequency offset (CFO) from an initial CFO, determining hypothesis test levels from the normalized CFO, and performing correlation using the received PSSS, a first sequence, a second sequence, a first sequence shifted per hypothesis test level and a second sequence shifted per hypothesis test level. When the number of hypothesis test levels is greater than 1, the shifted first sequence and the shifted second sequence having a complex conjugate relation in a predetermined normalized CFO value are correlated via the same correlator.