The invention relates to an integrated internally-installed forced wet-type self-locking cycloid hydraulic motor structure. The integrated internally-installed forced wet-type self-locking cycloid hydraulic motor structure is characterized in that a self-locking mechanism comprises a self-locking oil cylinder shell, the rear end of the self-locking oil cylinder shell is provided with a rear cover, a self-locking piston is arranged in the self-locking oil cylinder shell, one side of the self-locking piston and the self-locking oil cylinder shell form a sealing cavity, a self-locking friction plate pair is arranged in the sealing cavity and comprises a static friction plate and a movable friction plate, the static friction plate is connected to the self-locking oil cylinder shell, the movable friction plate is connected to a self-locking main shaft which is connected to a universal driving shaft, the other side of the self-locking piston and the rear cover form a cavity, a compressed spring is arranged in the cavity, a shuttle valve is arranged on the outer surface of the self-locking oil cylinder shell; an oil port I, an oil port II and an oil port III are formed in the shuttle valve; the oil port I and the oil port II are communicated with a stator-rotor pair through an oil channel, and the oil port III is communicated with the sealing cavity through the oil channel. The self-locking oil cylinder shell has the advantages of simple structure, small size, long service life, good reliability and low noise.