The utility model relates to a water and gas distributing device used for back flushing of a filter chamber, which comprises a vertical pipe and a transverse pipe. The vertical pipe is provided with an exhaust pore close to the top of a water and gas distribution dyke, and the lower side of the exhaust pore is provided with an entering air pore; the lower part of the vertical pipe is provided with a strip-shaped slot along the axial direction. Both ends of the transverse pipe are obturated, the top of the transverse pipe is provided with a plurality of exhaust pores at intervals, and the bottom is provided with a through hole which can be inserted in by the upper end of the vertical pipe; the transverse pipe is provided with a plurality of water distributing holes the outlets of which incline towards the side face at intervals close to the bottom of the filter chamber, and the transverse pipe is also provided with a plurality of gas distributing holes the outlets of which incline downwards at intervals at both side parts of the pipe body. A pre-embedded bushing used for positioning and fixing the vertical pipe also can be included. The water and gas distributing device is formed by adopting universal tubular product, has simple structure and convenient manufacture, can be processed directly by adopting the sale tubular product in the market, and can reduce the production cost. The installation is convenient, and jam can not easily occur.