This paper studies a new type of manipulator that can retain the freedom of rotation of the drill pipe in terms of its stability and safety in movement of the drill pipe. The manipulator improves the pressure-keeping retention effect through the accumulator during pump shut-off， and retains the rotational freedom of the drill pipe through the roller structure. In this paper， the multibody dynamic model of the manipulator and the supporting hydraulic control circuit are established， and the mechanic-hydraulic co-simulation is performed. Under the condition of changing the drill pipe diameter and the hydraulic circuit stress respectively， the clamping effect of the manipulator was observed. Through simulation， the clamping force change curve and the gravity position change curve of the drill pipe are obtained， the allowable pressure range of the hydraulic system is determined， and the movement smoothness of the drill pipe clamped with the single manipulator is verified to meet the requirements.