In order to provide firsthand reference data for model building and analysis of temperature field of seafloor hydrothermal vent, a temperature measurement sys- tem is designed, which can be used to measure the temperature of seafloor hydrothermal vent. The system can implement in situ multipoint temperature measurement and work for 15 days on the seafloor, so low power consumption design principle of the integrated circuit board is adopted. To enable the system to endure the high pressure on the seafloor, mechanical structure of the system is designed in terms of design principle of pressure container. The pressure test ex- periment was performed in the authoritative institution, and the results indicated that the system was safe and could work reliably on the seafloor. In the first Sino-American Joint Dive Cruise, the instruments were carried to the seafloor to work by Alvin. The experiment in the sea was successful, and the results indicated that the system could survive in the high pressure and high temperature environ- ment and record the temperature activities of hydrothermal vents. About 710000 groups of temperature data were acquired, and these are of importance for further scientific researches. In order to provide firsthand reference data for model building and analysis of temperature field of seafloor hydrothermal vent, a temperature measurement sys- tem is designed, which can be used to measure the temperature of seafloor hydrothermal vent. The system can implement in situ multipoint temperature measurement and work for 15 days on the seafloor, so low power consumption design principle of the integrated circuit board is endured the high pressure on the seafloor, mechanical structure of the system is designed in terms of design principle of pressure container. The pressure test was- periment was performed in the authoritative institution, and the results indicated that the system was safe and could work reliable on the seafloor. In the first Sino-American Joint Dive Cruise, the instruments were carried to the seafloor to work by Alvin. The experiment in the sea was successful, and the results indicated that the system could survive in the high pressure and high temperature environ- ment and record the temperature activities of hydrothermal vents. About 710000 groups of temperature data were acquired, and these are of importance for further scientific researches.