To study the characteristics of Micro-hotplate(MHP)based vaccum sensor at constant temperature working mode,the influences of working temperature and dimensions on the working characteristics of MHP-based thermal vacuum sensor at constant temperature was analyzed based on the thermal analysis of MHP.An MHP-based thermal vacuum sensor was designed in the supporting beams of 65 μm long and 21 μm wide,and the gas gap below micro-hotplate of 0.5 μm.The micro sensor was fabricated successfully with surface micromachining technology.The testing results show that the fabricated vacuum sensor is sensitive in pressure range of 2～10⁵ Pa and the sensor response characteristics are consistent with the theoretical calculated results.