Abstract: Insulin detection is significant in clinical study, but the lack of effective detection methods impedes its clinical applications. In this work, the carbon microelectrode fabricated with MEMS (micro-electromechanical system) and C-MEMS (complex micro-electromechanical system) technology is applied for insulin detection. The carbon microelectrodes were fabricated through the pyrolysis of photoresist and showed good electrochemical performance. After electro-deposition of ruthinium oxide nano particles on the electrode surface, the insulin oxidation is electro-catalyzed and its electrochemical detection is realized at 0.7 V. The sensor has a sensitivity of 1 nA/μM for insulin detection, with a detection limit of 800 nM. Electrochemical measurement shows that the sensor has advantages of high sensitivity, fast response and usability for real time on-site detection.