Abstract: Surface potential of coal rock during water-inrush process was tested through a simulated experiment system for surface potential of coal rock, and variation rule of the surface potential of coal rock during water-inrush process was researched. Following conclusions are gotten: The surface potential of coal rock has significant spatiotemporal response characteristics for water-inrush evolution, and can reflect internal rupture and crack expansion conditions of coal rock. Water bursting evolution is divided into three periods, namely incubation period, crack expanding period and systematical water-inrush period. The surface potential signals are relatively stable during incubation period, and fluctuate during crack expanding period and systematical water-inrush period. The surface potential signal level is usually different in different positions. In the same position, the surface potential signal level has positive correlation with pore water pressure or breaking intension of coal rock.