The invention discloses a secondary booster pump for oilfield water injection, and belongs to the technical field of petroleum water injection exploitation. The booster pump comprises a boosting system and a hydraulic driving system. The boosting system comprises a cylinder body, a piston body is arranged in the cylinder body, and the middle of the piston body closely fits the interior of the cylinder body; the left and right sides of the piston body are provided with plunger rods, and the left and right ends of the plunger rods and the interiors of the two ends of the cylinder body form isolated high-pressure water chambers; the portions, in the middles of the plunger rods on the left and right sides, of the interior of the cylinder body are provided with plugging devices, isolated hydraulic oil chambers are formed between the piston body and the plugging devices on the left and right sides, and the hydraulic oil chambers are connected with the hydraulic driving system; and the portions, at the ends of the high-pressure water chambers, of the two ends of the cylinder body are connected with a water supply network pipe through water inlet check valves, and the portions, at the upper parts of the high-pressure water chambers, of the two ends of the cylinder body are connected with a well through water outlet check valves. According to the booster pump, the hydraulic pressure ofan existing pipe network is utilized, the boosting system is used for supplementing pressure on the basis of the pressure, and then the final hydraulic pressure meets the injection requirement of thewell.