The invention discloses an electric energy quality monitoring and controlling system. The electric energy quality monitoring and controlling system mainly comprises a shared memory data interaction module, a parameter read-write module, a DPRAM read-write module, a timed recording module, a high-speed recording module, a qualified rate statistics module, an out-of-limit monitoring module and the like, and further comprises a DI monitoring module high in requirement for real-time performance, a DO control module, an electric energy measurement module and a PPC memory management module. The working processes comprise the steps of initializing a PPC system, creating a thread, creating shared memory, loading a driving device, reading calculation factors, reading parameters, and carrying out data logical operation, transmission, data storage and communication. The electric energy quality monitoring and controlling system can carry out advanced electric energy quality analysis and high-precision measurement, monitor electric energy quality in real time and make electric energy consumers obtain various operating data of electric energy in the first time, and therefore the electric energy quality can be assessed and monitored fully, and the strategy and scheme for improving the electric energy indicators can be proposed.