The invention provides an underwater manipulator clamping jaw structure, which consists of a claw I1, a claw II 23, an external connecting rod I 2, an external connecting rod II 3, an internal connecting rod I 4, an internal connecting rod II 5, a rubber layer I 6, a rubber layer II 7, an external connecting rod pin I 8, an external connecting rod pin II 9, an external connecting rod pin III 10, an external connecting rod pin IV 11, an internal connecting rod little pin II 13, an internal connecting rod little pin III 14, an internal connecting rod little pin IV 15, an internal connecting rod large pin II 17, a hydraulic cylinder pin 18, a base 19, a wrist 20, a hydraulic cylinder 21, a connecting rod I 22, and a connecting rod II 24.The invention is used for an underwater robot and has the advantages of simple structure, light weight, and agile movement. By the driving of the hydraulic pressure, the opening/closing movement of the clamping jaw is realized, and the clamping jaw is provided with the capability of clamping lager load; by the small range movement of the hydraulic cylinder piston, the opening/closing movement in large range of the clamping jaw is realized.