In recent years, more attention has been gradually paid to the protection of marine ecological environment and more marine environmental monitoring activities and related researches have been carried out frequently. Among them, water quality monitoring is one of the key research contents, and the water quality online monitoring method can solve the problem of insufficient timeliness of traditional manual fixed-point sampling monitoring. Based on the technology of Internet of Things (IoT), a practical online monitoring scheme of near-shore water quality is designed. By integrating the LoRa wireless communication technology characterized by long communication distance, strong anti-interference ability, low power consumption and low cost, the sensor technology, the Web technology and the Wechat small program technology, this scheme can make it possible to realize the real-time collection, processing, transmission, storage, sharing, display and control of near-shore water quality monitoring data and meet the needs of various offshore fixed point monitoring applications, such as near-shore water quality monitoring, fishery and aquaculture monitoring and marine pasture monitoring. In addition, the implementation and testing of the prototype system of the designed scheme are also carried out. The results show that the designed scheme can support the intelligent and long-term remote monitoring of near-shore water quality in a wireless way and effectively improve the shortages of the existing near-shore online observation systems, such as short monitoring distance, high cost, not flexible enough layout, poor anti-interference, and so on.