The utility model provides a rotating-cylinder hydraulic motor and a pump employing same. The rotating-cylinder hydraulic motor is characterized in that the inner cylindrical surface of an outer sleeve is arranged coaxially with the outer cylindrical surface of a main shaft; the outer cylindrical surfaces of the rotating cylinder and the main shaft are internally tangent to the inner cylindrical surface of the outer sleeve, the rotating cylinder is connected in a sliding manner through eccentric sleeves at the two ends, the main shaft is fixedly connected with a partition plate, a through opening is formed on the rotating cylinder, and the partition plate penetrates the opening of the rotating cylinder and is in sliding connection with the inner cylindrical surface of the outer sleeve. The utility model has the advantages of constant output torque, little pressure oscillation, easy process, low manufacturing cost, and suitability for a hydraulic transmission machine, a hydraulic spanner, a drilling tool, a building tool, a mining tool as well as for an oil pumping machine and a liquid conveying pump.