The invention discloses a gravity flow water quality current divider. The gravity flow water quality current divider comprises a current divider body, wherein the current divider body comprises an upper cover plate, a rotating apparatus, an elbow, a water receiving hopper, and a shell, wherein the rotating apparatus is fixed on the upper cover plate, and the rotating apparatus comprises an upper rotating body, a lower rotating body and a ring-shaped component; the upper part of the elbow is communicated with the lower end of the lower rotating body, and the elbow can be driven by the rotatingapparatus to rotate by adopting the center axis of the rotating apparatus as an axis; the water receiving hopper is arranged below the elbow, the lower part of the water receiving hopper is communicated with a water outlet pipe, and when the rotating apparatus rotates to a predetermined angle, the lower part of the elbow is communicated with the water receiving hopper; and a water inlet pipe is fixed on the top of the shell, the elbow, the rotating apparatus and the water receiving hopper are arranged in the shell, and a water outlet pipe extends out of the lower end of the shell. The gravityflow water quality current divider has the characteristics of simple structure, convenience in installation, flexibility in operation, stability in operation and the like, the pollution can be effectively prevented, and the rainy water utilization efficiency can increased. Since the gravity flow water quality current divider has no structure such as a valve, a tee joint and the like, the loss of water head can be reduced, the discontinuous rainy water division can be realized, and the blockage problem can be avoided.