The present invention discloses a power head of a vertical reciprocating pump with multi-spherical connection, and a water injection pump using the same, which includes a hydraulic end, a centralizing sleeve, an adjustable ball seat, a circular pull-back plate, pull rods of the power head, and a hydraulic end, an integrated base and the alike. By using the structure with multiple movable spherical surfaces, the error of the oblique disk during its motion along the elliptic trajectory can be eliminated. The power end can be linked with hydraulic ends and can be applied to boosting water injection processes for feeding liquid at low pressure or feeding liquid at high pressure in oil fields and various high-pressure liquid delivery fields. The fast on-site installation of the water injection pump of the present invention can be realized by the integrated base, so as to save the investment and improve the safety factor.