The invention aims at providing a water hydraulic driving device. According to the water hydraulic driving device, a motor drives a ball screw assembly and a sleeve end cover to move rightwards and drives a water hydraulic cylinder piston rod to move rightwards, a water hydraulic cylinder A discharges water, a water hydraulic cylinder B sucks water, a one-way valve A is switched on to discharge water out of a system, a one-way valve D is switched on to suck water into the system, and a one-way valve B and a one-way valve C are switched off; when the sleeve end cover triggers a travel switch 2 during rightward movement, the motor reversely drives the ball screw assembly to drive the sleeve end cover to move leftwards, the water hydraulic cylinder A sucks water, the water hydraulic cylinder B discharges water, the one-way valve A is switched off while the one-way valve C is switched on to inwardly suck water, the one-way valve B is switched on to outwardly discharge water while the one-way valve D is switched off, and the motor is switched over again until the sleeve end cover continues to move leftwards and touches a travel switch 1, so that the water hydraulic system can continuously supply a hydraulic source to the outside. The water hydraulic driving device has the advantages of compact structure, convenience in mounting and the like and has the characteristics of hydraulic pulsation reduction and high-precision small-flow control.