The invention provides a multi-parameter water quality monitoring system based on a micro-optical-electro-mechanical system (MOEMS) micro spectrometer. The multi-parameter water quality monitoring system consists of an optical detection system, a multi-sample/reagent introducing flow path system, a singlechip-based circuit control system, an embedded-type measuring and controlling system and a wireless transmission module, wherein the multi-sample/reagent introducing flow path system is used for delivering samples and reagents into the optical detection system; output signals of the optical detection system are connected to the embedded-type measuring and controlling system; the embedded-type measuring and controlling system controls the singlechip-based circuit control system from an upper layer; the multi-sample/reagent introducing flow path system consists of a flow path system which consists of a multi-position valve and a peristaltic pump of a miniature stepping motor; and the optical detection system consists of a collimating light source, a multi-functional miniature sample detection chamber and an MOEMS micro spectrometer. The multi-parameter water quality monitoring system has a function of efficiently and rapidly switching flow paths, has the advantages of higher sample extracting precision, rapidness in detection and high efficiency for cleaning, and can be widely applied to real-time monitoring of quality of surface water grade II.