The invention discloses an oil well pump and relates to the technical field of oil exploitation. The oil well pump comprises a pump cylinder unit, a plunger unit, a casing pipe and a fixed ball valve unit, wherein the pump cylinder unit comprises an outer pipe made of metal and a plurality of pump cylinders made of ceramics and arranged inside the outer pipe; a first gasket is arranged between every two adjacent pump cylinders; the diameter of the outer pipe is smaller than that of each pump cylinder; the plunger unit is arranged inside the pump cylinders and comprises an upstream movable valve unit, an inner pipe made of metal and connected with the upstream movable valve unit through a plunger upper connector, a plurality of plungers made of ceramics and arranged outside the inner pipe, and a downstream movable valve unit connected below the inner pipe and the plungers through a plunger lower connector; a second gasket is arranged between every two adjacent plungers; a first belleville spring is arranged between the plunger upper connector and the plungers; the lower end of the first belleville spring is used for abutting against the upper end of the plungers; the casing pipe is connected with the outer pipe and internally connected with a connection pipe used for abutting against the plunger unit; a second belleville spring used for abutting against the pump cylinders is arranged between the casing pipe and the connection pipe; and the fixed ball valve unit is connected with the casing pipe and located below the plunger unit.