A high speed on-line annular rainwater filter comprises a cylindrical tank. The tank comprises a top cover and a tank main body; the top cover and the tank main body are detachably connected with each other; an exhaust valve is arranged on an upper part of the tank; a lower part of the tank is provided with an effluent trough; the effluent trough is provided with a water outlet; the tank is provided with a plughole communicating the tank inside and the effluent trough; a vertical water inlet pipe passes trough the tank; an upper end of the water inlet pipe is above the top cover and communicates with a rainwater down pipe; a lower end of the water inlet pipe is below the tank main body and connected with a detachable end cap; and the water inlet pipe is in seal connection respectively with the top cover and the tank main body. The filter spends no power cost and carried out on-line direct filtering to ensure the filtering effect; meanwhile, the filter has advantages of simple structure, low equipment cost and filtering cost, no water volume regulating reservoir, no backwashing, fast filtering, large filtering flow and obvious filtering effect.