This paper presents the results of design, installation and field measurement of a prototype underwater-turbine-generator-based micro hydro power (MHP) generation system. The studied MHP system employs the flowing water energy of the agricultural irrigation of one of the irrigation ditches of Yunlin Farmland Irrigation Association, Taiwan. Fundamentally, the irrigation ditches are used to distribute irrigation water to different farmlands. Design of a MHP has to meet practical conditions of the selected ditch such as depth, width, water flow rate, days of water flowing, etc. The designed MHP unit consists of a prototype underwater turbine, a gearbox, a three-phase self-excited induction generator with a switchable excitation capacitor bank, a three-phase diode bridge rectifier, a DC-to-DC buck converter, and a DC-to-AC inverter. An embedded-system-based monitoring and control system of the MHP unit is also properly designed to measure the electrical data of the MHP system. According to the field measurement results, the designed prototype underwater-turbine- generator-based MHP system can stably offer adequate electric power to the connected loads.