A plunger pump, applied to a high-pressure medium conveying device. The plunger pump comprises a fixed assembly, a movable assembly, and a fault diagnosis module; the movable assembly is provided on the fixed assembly; and the movable assembly is movable with respect to the fixing assembly. The fault diagnosis module comprises a temperature sensing assembly (100) and a processing unit (200); the fixed assembly is provided with a temperature measurement hole; the temperature sensing assembly (100) is at least partially located in the temperature measurement hole; the temperature sensing assembly (100) can be in contact with a lubricating oil flowing through the movable assembly; the processing unit (200) is connected to the temperature sensing assembly (100); and the processing unit (200) performs monitoring and fault diagnosis on the plunger pump according to a temperature value sensed by the temperature sensing assembly (100). The solution can solve the problem that the plunger pump needs to be dismantled and overhauled blindly.