Abstract: Based on the ocean current data observed by mooring systems in the western continental slope region of the Dongsha Islands in northern South China Sea, the structural and statistical features of energy and energy flux of the mode-1 internal solitary waves (ISWs) are studied. The results indicate that the energy of the mode-1 ISWs is mainly confined in upper layers of the region. Kinetic energy ( E_\mathrmK ) is mainly in 0-100 m depth and reaches its maximum at sea surface, while available potential energy ( E_\mathrmA\mathrmP ) is mainly in 50-150 m depth and is 0 at sea surface. The ratio of E_\mathrmK to E_\mathrmA\mathrmP increases with amplitude, and is about 0.98 when amplitude is less than 60 m and about 1.60 when the amplitude is greater than 60 m. In observation period, total energy is highest in September, and average energy is highest in December. The energy flux of the mode-1 ISWs is negative and mainly confined in upper layers of theregion. The nonlinear advection term is significantly smaller than the velocity-pressure term, with a statistical ratio of about 0.34. In observation period, the total energy flux is highest in August, and the average flux is highest in December. By comparing the results of two sets of subsurface buoy observations in the basin area and the eastern continental slope region of the Dongsha Islands, significant energy loss is found during the propagation of ISWs from the basin region to the continental slope region, and E_\mathrmA\mathrmP/E_\mathrmK is greater than that in eastern continental slope region of the Dongsha Islands, which is possibly due to the steep topography in eastern continental slope region that leads to wave steepening and conversion of E_\mathrmK to E_\mathrmA\mathrmP . The overall nonlinearity of ISWs in the observation region is smaller than that in eastern continental slope region but stronger than that in the basin region, and local energy dissipation is strong in the region.