The invention discloses an intercepting filter on-line treatment pool and a control method thereof, and a rainwater treatment system. The intercepting filter on-line treatment pool comprises a pool body as well as a water inlet and a water outlet which are formed in the pool body, and also comprises a blocking wall arranged in the pool body; the blocking wall partitions the pool body into a waterpassing gallery and a filter treatment area; a particle filtering device and a water discharging device are arranged in the filter treatment area; a water inlet hole is formed in the part, which is positioned on a first area, of the blocking wall; the water inlet hole is used for communicating the filter treatment area and the first area; and the water discharging device is used for communicatingthe filter treatment area and a second area. The intercepting filter on-line treatment pool is simple in structure and convenient to operate; and the on-line treatment pool can deeply filter rainwaterat the early stage of rainfall, can draw off floodwater rapidly when the flow quantity is high, can reduce pollution to a natural water body and can guarantee the rainwater treatment effect of the rainwater treatment system.