The invention discloses a plunger pump fault diagnosis method and diagnosis system. A diagnosis system is included and comprises a fault parameter platform, a cloud server, a circuit diagnosis module and a warning module, and the fault parameter platform provides information storing fault parameters and provides a function of changing equipment parameters; the cloud server is used for summarizing and storing the fault parameters and realizing online real-time sharing; the circuit diagnosis module is in contact with an electricity measuring instrument to eliminate measurement circuit faults; and according to instrument fault diagnosis, interconnection and intercommunication of monitoring and tracking, online monitoring, predictive maintenance, fault early warning, diagnosis and repair, operation optimization and remote upgrading are carried out on automatic hardware, instruments, sensors and controllers, and the fault parameter platform, the cloud server, the circuit diagnosis module and the warning module are communicated with one another. An intelligent detection method is adopted, the diagnosis efficiency is greatly improved, equipment maintenance is facilitated, and the method is relatively practical.