An easily disassembled impeller-type flow sensor, comprising a housing and an impeller-type sensor assembly, the housing includes an impeller chamber, a water inlet port communicated with the impeller chamber, a water outlet port communicated with the impeller chamber, and a water outlet port communicated with the impeller chamber The assembly seat of the base also includes an open retaining ring, the part of the lower part of the steps of the base is liquid-tight with the assembly seat at the lower part of the inner ring platform, and the steps are supported and matched with the inner ring platform; the radially outer side of the open retaining ring is embedded in the ring The inside and the radial inner side of the card slot cooperate with the radial edge of the top of the base. Due to the adoption of such a structure, when the impeller sensor assembly is disassembled, especially in the environment where the pipeline is densely covered and a wrench cannot be used, it is only necessary to disassemble the opening retaining ring with bare hands or needle-nose pliers; and then it can be removed by hand without any tools. The impeller sensor assembly is taken out and disassembled easily. When assembling, just insert the impeller assembly into the impeller chamber with bare hands, and then assemble the opening retaining ring, which is convenient for assembly.