The invention relates to a method for forming an ecologically-
sewage-purifying compound riverbed 
wetland system, which is characterized in that: a 30-60mm round gravel, a 12mm medium gravel, a 6mm gravels as well as coarse sands and soil matrixes are filled in the new riverbed from the lower part to the upper part to form a compound riverbed and the top of a 
shoal of the compound riverbed is positioned below the low 
water level of the river; the aquatic plants are planted on a soil layer of the 
shoal of the compound riverbed; the deep grooves and the slopes are protected and built by ecological concrete; thus, the ecological ecologically-
sewage-purifying compound riverbed 
wetland system is formed. The invention has the advantages that a comprehensive 
treatment system with the 
plant-the matrix-
microorganism is formed, thus enhancing self-purification capability of the river, purifying 
water body of the river and improving water 
environmental quality of the river; section form of the riverbed is transformed into a compound riverbed structure in which the 
shoal and the deep grooves exist simultaneously and the riverbed 
wetland system is arranged in sinuous way in longitudinal river, which facilitates 
perch and growth of the aquatic creature and diversification of the river creature; a water 
distributor is laid to carry out the depth treatment for 
tail water reaching the standard; the invention has the advantages of simple structure and construction, convenient operation, 
stable function and low manufacture cost.