The invention provides a smart grid-oriented power quality monitoring system and a smart grid-oriented power quality monitoring method, which relate to the field of monitoring of power quality. The system comprises a distributed online/offline node detection module, a network communication module, a distributed database module and a comprehensive management module of the power quality monitoring system, wherein the distributed online/offline node detection module comprises a parallel analog-to-digital conversion module and a signal processing module so as to realize distributed detection of asmart grid. In the technical scheme provided by the invention, a plurality of analog-to-digital conversion chips are connected in parallel and an analog signal is sampled, so that high-accuracy sampling rate of signals is increased and the detection requirement on transient power quality signals is met; based on a programmable logic chip, online analysis and data compression are realized by a parallel signal processing algorithm; a distributed database is adopted, so that system reliability is enhanced and system upgrade is promoted; and a global positioning system (GPS) and a communication network module are adopted, so that a distributed network system is realized, and power quality monitoring of the smart gird is supported powerfully.