The invention relates to a composite biological trickling filter for denitrification and dephosphorization, belonging to the technical field of sewage treatment. The biological trickling filter is cylinder-shaped and comprises a water distributing area, a stuffing layer and a water catch area from top to down; wherein, the water distributing area comprises a plurality of rollers, a rotary water distributor, a water inlet pipe, a water pipe, a water sprayer and tracks; the water inlet pipe is connected with the rotary water distributor, the rotary water distributor is connected with the water pipe which is provided with a water outlet, the water sprayer is positioned below the water pipe and is connected with the rollers; five layers of grid frames are arranged vertically in the stuffing layer, and the grid frames separate the stuffing layer into a grid structure, so that the stuffing layer is successively separated from bottom to top into a stone and sand layer, a composite steel slag stuffing layer, a plaster stuffing layer, a sawdust stuffing layer and a coke layer; the water catch area comprises a header tank, a water outlet pipe and a water catch plate, wherein, the header tank is positioned at the bottom of the trickling filer, and the water outlet pipe is connected with the header tank. By introducing the grid frames, the composite biological trickling filter has the advantages of eliminating the problems of the filter blockage, water accumulation and other defects, effectively improving the aerobic bacteria processing performance of the composite biological trickling filter, efficiently removing COD and simultaneously achieving the effects of denitrification and dephosphorization.