Before the implementation of engineering projects,it is essential to determine the detailed distribution of underground spaces in the work area.The deployment of a 3D high-density electrical observation system is difficult,and using conventional electrical equipment for acquisition is time-consuming,especially in complex geological conditions.By using parallel electrical acquisition technolo-gy,efficient data acquisition can be achieved.To accurately determine the three-dimensional morphology of the area where possible leak-age pipes may form in the lower part and surrounding areas of a phosphogypsum stacking yard,parallel electrical acquisition was used to collect data,combined with actual geological conditions.The three-dimensional electrical exploration data volume under the true three-di-mensional observation system in the measurement area was obtained,and the data was processed and interpreted with three-dimensional inversion with terrain.The results show that 3D parallel high-density electrical observation can effectively and accurately reveal the distri-bution of underground spaces on the site.A total of 5 abnormal areas were delineated during the on-site exploration.The results were con-sistent with the drilling exposure data and provided accurate basis for guiding the construction of anti-seepage curtains in the later stage.