Water quality monitoring plays an important role in contamination control and environment protection. This paper describes an on-line multiparametric water quality monitoring system based on visible spectrophotometry, which combines embedded technology with GPRS telecommunication technology. This system can realize online wireless monitoring to concentrations of chromium (Cr), plumbum (Pb), A surfactant (AS), chemical oxygen demand (COD), ammonia nitrogen (AN), total phosphorus (TP) and total phenol (TPh) in real time. The mechanical structure, hardware circuit and software design of the system are completed. The absorption spectrums of pure water and MB-SDS complex have been measured. Preliminary experiments using a model machine show that each mechanism of the system runs well. Moreover, the monitor possesses many advantages, such as high degree of automation, high reliability, high efficiency, compact structure, small size, and so on.