An internally curved low-speed high-torque hydraulic motor with torque being output by means of the rotation of a housing, comprising: a left bearing block, a right end cover, a cylinder body, an internally curved cam ring, a spacer ring, an axial oil distribution pan, and a plurality of radially arranged plunger assemblies, wherein the internally curved cam ring, the left bearing block, the spacer ring and the right end cover form a motor housing; the motor housing with a split structure is formed by connecting the internally curved cam ring, the left bearing block, the spacer ring and the right end cover in series via high-strength bolts; the motor as a whole is combined by the fixed cylinder body and the rotatable motor housing; the motor housing rotates around the cylinder body, while the cylinder body is fixed; the axial oil distribution pan is axially arranged on one side of the cylinder body, and connected to an oil passage of the cylinder body through an oil passage; plunger holes of the cylinder body are designed in a single row or a plurality of rows depending on the magnitude of output torque, and the plurality of plunger assemblies are uniformly arranged in the plunger holes in a radial direction around the cylinder body; characterized in that the axial oil distribution pan further comprises: a spring configured in the axial oil distribution pan, and a balancing plunger configured in the axial oil distribution pan, wherein the balancing plunger is cup-shaped, wherein the spring is against a cup bottom of the balancing plunger, and an outer surface of the cup bottom of the balancing plunger tightly fits the right end cover; under the action of acting forces and reacting forces, acting forces of the spring and the balancing plunger cause contact surfaces between the axial oil distribution pan and the cylinder body to be always in tight fit; when pressurized oil enters, the axial oil distribution pan relies on the joint action of the spring, the balancing plunger and the pressurized oil to cause the contact surfaces between the axial oil distribution pan and the cylinder body to be always in tight fit; in the case where wear occurs, the acting forces of the spring and the balancing plunger are used to cause the contact surfaces between the axial oil distribution pan and the cylinder body to maintain close contact, thereby compensating for the wear, compensating for the wear and tear of the axial oil distribution pan, reducing leakages in the internal of the motor. a spring configured in the axial oil distribution pan, and a balancing plunger configured in the axial oil distribution pan, wherein the balancing plunger is cup-shaped, wherein the spring is against a cup bottom of the balancing plunger, and an outer surface of the cup bottom of the balancing plunger tightly fits the right end cover; under the action of acting forces and reacting forces, acting forces of the spring and the balancing plunger cause contact surfaces between the axial oil distribution pan and the cylinder body to be always in tight fit; when pressurized oil enters, the axial oil distribution pan relies on the joint action of the spring, the balancing plunger and the pressurized oil to cause the contact surfaces between the axial oil distribution pan and the cylinder body to be always in tight fit; in the case where wear occurs, the acting forces of the spring and the balancing plunger are used to cause the contact surfaces between the axial oil distribution pan and the cylinder body to maintain close contact, thereby compensating for the wear, compensating for the wear and tear of the axial oil distribution pan, reducing leakages in the internal of the motor.