The monitoring of water quality parameters such as DO, pH, salinity and temperature are necessary for the health of seafood such as sea cucumber. However, traditional monitoring system is based on cable data acquisition that has many disadvantages. Nowadays, GPRS is the most commonly accepted way for wireless transmission. Based on it, a type of low energy consumption RTU is developed and applied. In this paper, details of the design are introduced. In hardware design of this type of RTU, STM8L152 is selected in the MCU module to accomplish the function of ultralow power consumption, and solar battery is designed to solve the problem of power supply. In software design of the RTU, the sleep/online mode conversion is programed to reduce the energy consumption. It is comparatively low-priced and can detect necessary parameters for aquaculture. Performances of the RTU are tested in experimental stations and compared with two advanced water quality analyzers. Results show that it shows almost the same variation characteristics as those of HACH and YSI.