The invention discloses a wind driven generator hydraulic pitch-variable mechanism and system. The mechanism comprises a hub, a hydraulic cylinder, a web, a connecting shaft and a pitch-variable bearing, the web is connected with the inner ring of the pitch-variable bearing, the outer ring of the pitch-variable bearing is connected with the hub, the tail of the hydraulic cylinder is connected withthe hub through a hinge pin, the end of the hydraulic cylinder is connected with the web, so that the hydraulic cylinder, the web and the hub form a crank and connection rod mechanism, and linear reciprocating motion of the hydraulic rod and circumferential rotary motion around the hinge pin are transformed into circumferential rotary motion of the web. The wind driven generator hydraulic pitch-variable mechanism and system have the advantages of being simple and reliable in structure, high in response frequency and large in torque.