A good method to find hydrothermal vents is to detect the abnormal concentration of dissolved inorganic carbon in deep ocean. The authors have designed a dissolved inorganic carbon microelectrode based on polydimethylsiloxane（PDMS）gel and Zinc-Aluminium-hydrotalcite (Zn-Al-LDH) ion carrier complex membrane, which can be used to detect deep-ocean inorganic carbon abnormality. This dissolved inorganic carbon microelectrode is miniature, and can conveniently be integrated in the same probing cavity with pH microelectrode, salinity meter, temperature sensor, oxidation-reduction potential sensor, etc. to detect various in-situ signals. It has been tested in the laboratory condition, together with Ag/AgCl reference microelectrode, connecting with the input of Keithley 6517A high-resistant potentiometer. It was shown that the signals responded well to different concentrations of NaHCO3 solutions, with 30-60 second c.a. response time and a limiting range between 10－1 and 10－4 mol?L–1.