A novel online swimming pool water monitoring system comprises a controller, an operating switch, a thermograph, a turbidity meter, a pH (potential of hydrogen) meter, a residual chlorine comparator, an information display module, a lift pump, a circulating pump, a wireless transceiver, an Internet or GPRS (general packet radio service) and a data management center. The operating switch, the thermograph, the turbidity meter, the pH meter and the residual chlorine comparator are respectively in input connection with the controller, the information display module, the lift module and the circulating pump are respectively in output connection with the controller, the wireless transceiver is connected with the controller, and the data management center is in interaction with the controller through the Internet or GPRS. By the arrangement, monitoring automation can be realized, deterioration of swimming pool water quality can be forecast, and online querying and sharing of water quality information can be realized.