The invention discloses an upper limb rehabilitation robot. The robot is characterized in that the robot comprises a base and upper limb mechanical arms which are arranged on the base; each upper limbmechanical arm comprises a big arm mechanism, a small arm mechanism, a hand mechanism and a driving device; each big arm mechanism comprises a big arm supporting part, a big arm sliding block and a screw rod screw pair length adjustment device; each small arm mechanism comprises a small arm supporting part and a small arm length adjustment device; each hand mechanism comprises a handle, a handleconnection rod and a handle fixing rod which are connected in sequence; each driving device comprises a big arm pneumatic driving air cylinder and a small arm pneumatic driving air cylinder; one end of each big arm pneumatic driving air cylinder is fixed on a base support, the other end of each big arm pneumatic driving air cylinder is connected with the corresponding big arm supporting part, oneend of each small arm pneumatic driving air cylinder is connected with the corresponding big arm supporting part, and the other end of each small arm pneumatic driving air cylinder is connected with the corresponding small arm supporting part. The upper limb rehabilitation robot is compact in overall structure, reliable in performance and convenient to use and can lower the treatment cost of patients.