Abstract: This paper describes a monitoring system of real-time soil water content from both perspectives of hardware and software. The system consists of an ATmega128 microcontroller with embedded μC/OS-Ⅱ operating system, BD-Ⅰ type soil moisture sensors, RS-485 and RS-232 bus-based data transmission technologies. Compared with traditional microcontroller monitoring systems, the reliability and processing ability of the system are improved greatly by adding the μC/OS-Ⅱ operating system, which brings real-time multi-task processing capabilities. The system has significances in improving water utility efficiency and precise irrigation control in urban greening as well as agricultural and forestry production.