Abstract: Internal solitary waves (ISWs) in northern South China Sea are very active, featured by strong nonlinearity, high intensity, and concentrated energy. Their propagation characteristics and fine-scale structures are complicated under the influence of background processes, increasing the difficulties in predicting ISWs and conducting offshore operations of oil platforms. Based on a mooring deployed at a water depth of 295 m in the Lufeng area in northern South China Sea for 79 days, the property and temporal variation of the ISWs were carefully analyzed. The typical ISW appeared as wave trains with a leading wave amplitude of up to 86.7 m, and induced local warming of more than 8.0 °C and the maximum westward and northward currents of up to 0.83 m/s and 0.60 m/s in upper layer, respectively. The statistical results showed that 91 ISWs captured during observation period mainly propagated northwestward with an average amplitude of 59.9 m and a mean value of up to 0.79 m/s in upper layer. Moreover, the ISWs occurred more frequently and stronger during 04:00-06:00 and 16:00-19:00 and on the 2^nd-5^th and 16^th-19^th lunar days. In addition, thermocline depressed by the diurnal and semi-internal tides formed an elevation soliton in the typical ISWs, which caused local cooling of 1.3 °C and westward and northward currents of more than 0.3 m/s and 0.2 m/s near sea bottom, respectively. The steep front of the elevation soliton converge enhanced shear, making it prone to trigger shear instability. This study provides important references for offshore construction of oil platforms and survey operations in the Lufeng area.