The utility model relates to a water conservancy whirl auxiliary rock breaking instrument in pit, including top connection and lower clutch, be provided with drilling fluid transfer passage hole in the top connection, be provided with the lower clutch centre bore in the lower clutch, lower clutch centre bore inner sealing sleeve is equipped with and seals the reposition of redundant personnel tubesocket that separates the lower clutch centre bore, be provided with awl section of thick bamboo swirler in the lower clutch centre bore, it follows the guiding gutter that the inner wall tangentialof awl section of thick bamboo swirler got into to be provided with the permission drilling fluid on the lateral wall of the big footpath end of awl section of thick bamboo swirler, the big footpath end of awl section of thick bamboo swirler seals the inner chamber of wearing to be equipped with can communicate an awl swirler and the shunt tubes of drill bit, the outside one -way intercommunication of outside annular space ab intra with water conservancy whirl auxiliary rock breaking instrument in pit can be followed to the path end of awl section of thick bamboo swirler. The separation of shaft bottom drilling fluid solid phase can be realized to this instrument, reduces drill bit drilling fluid density of department and annular space liquid column pressure, reduces the chip hold down effect, alleviates the drill bit wearing and tearing, extension bit life.