The invention discloses an adjustable knee joint rehabilitation device with a massage function. The adjustable knee joint rehabilitation device comprises a main body part, a pair of angle adjusting parts, a pair of reciprocating driving parts and a pair of leg fixing parts, wherein the main body part comprises an L-shaped base, a sitting plate, side plates and a fixing seat. By turning a rotatinghandle, an arc-shaped strip drives the shank to overturn upwards, when severe pain is felt at the knee joint, turning of the rotating handle is stopped, that is, namely leg bending angle adjustment iscompleted, the reciprocating driving parts drive a ']'-shaped sliding block to reciprocate upwards and downwards to drive the arc-shaped strip to overturn a specified angle, accordingly the shank isbent at a proper angle, the knee joint is exercised by reciprocated bending at the bending angle, the recovery of the knee joint of a patient is facilitated, and the exercise enthusiasm of the patientis improved. In addition, a piston is driven to move left and right in the piston barrel through a hinged rod II and a piston rod to enable an air bag to expand or contract for shank massage, the blood circulation is improved, and the muscle atrophy of the shank is prevented.