Abstract: Based on the observational data from two moorings deployed in the northern South China Sea, the spatiotemporal variation of internal tide (IT) in the oil and gas field is investigated. The results show that IT at the station LF2 was stronger and the maximum baroclinic tidal current was 8.3 cm∙s⁻¹, which appeared at 290 m depth. Wavelet and energy analysis show that the energy of semidiurnal IT was 1-2 orders smaller than that of diurnal IT in magnitude. The vertical structure of diurnal IT at LF2 was dominated by the second mode while the semidiurnal IT was dominated by the first mode. The diurnal IT at LH2 was dominated by the first mode, but the semidiurnal IT was characterized by both the first and second modes. The averaged propagation directions of diurnal IT at the two mooring ststions were both close to due north, while the semidiurnal IT propagated mostly northwestward. However, in mid October, the semidiurnal IT propagation direction at LF2 changed from northwest to southwest, and the diurnal IT propagation direction at LH2 changed from north to northeast. With the analysis of background flow, it is found that the change of IT propagation direction in mid October is probably caused by the change in background field. These findings will help to deepen our understanding of the temporal and spatial characteristics of ITs in the continental shelf area and promote our understanding on the variation mechanisms of the IT in the oil and gas field in the northern South China Sea.