The utility model discloses a tunnel fire-fighting system using slope flow water and pavement water as a water source. The slope flow water is used as the water source, so sufficient water retention capacity of a reservoir can be guaranteed and meanwhile the cost is reduced; the interception and drainage ditches are constructed on a plurality of contour lines of a slope to collect slope rainwater, so the water source is more convenient to collect, and the cost is also low; meanwhile the pavement water is used as the water source to supplement the slope flow water, so the water source is fuller; torrent tanks are constructed to collect the slope flow water of interception and drainage ditches, and the water speed is relieved by the torrent tanks with included angles with the interception and drainage ditches; an energy dissipation dam is arranged between the torrent tanks and the water filter pool, so the water speed is further reduced and a water filter pool is protected; a water quality sensor is matched with a switching mechanism, sewage is drained to a sewage pool when the water quality is unqualified, and qualified water is drained to a high-level pool, so the corrosion of an acidic substance in sewage to a fire hydrant and a pipeline is avoided; by arranging a low-level pool, a pump room and the high-level pool, water pressure can be automatically provided for a tunnel fire hydrant.