The invention discloses a tunnel fire-fighting system of utilizing water of valleys and between mountain as a water source, which comprises a drainage ditch and a water retaining dam, a water filter, a sand sediment trap, a low-position pool, a pump room, a high-position pool and a tunnel fire hydrant which are built near the tunnel; water of valleys and between mountain is used to be as the water source, so that the adequate water storage of a reservoir is ensured, meanwhile, the cost is reduced; the water retaining dam is built at the tail end of the drainage ditch, the water in the drainage ditch is intercepted and stored by the water retaining dam; in a dry season, more water between mountains can be stored by virtue of the relatively high water storage of the water retaining dam; the low-position pool, the pump room and the high-position pool are arranged, so that the water pressure can be automatically provided for the tunnel fire hydrant.