The invention relates to a seawater/freshwater axial plunger hydraulic pump that is belonged to positive displacement type pump. It decreases the attrition of working in seawater/freshwater medium and decreases the request to the attrition of the material. Plunger holes are equally set on the cylinder body. And the plunger and the plunger hole are sliding matched. The input shaft is installed on the carcass of the pump by supporting bearing. The end surface crankshaft is formed on the input shaft, and the sloping cam plate is installed at the crank of the end surface crankshaft by supporting bearing. The direction guiding location slider is installed outside the sloping cam plate that sliding matched to the direction guiding slide groove. The sloping cam plate is actively connected to the plunger. The universal ball pivot at one end is installed on the reference circle and the ball pivot at the other end is connected to plunger. The pump is tightly structure, light weight, stable capability, and large flux. It could be used as drive component of liquid transferring using seawater/freshwater and other low viscosity liquid or liquid driving system.