Abstract: A new kind of marine electrode for electric field test was prepared by modifying carbon fiber with urea, and its electrochemical and electric field response performances were tested. The results show that the oxygen-containing and nitrogen containing groups on the surface of carbon fiber have significant effects on its electrochemical performances. The carbon fiber electrode treated with urea at 450℃ has the lowest internal resistance and maximum specific capacitance. The electrochemical performances also directly affect the electric field performances of its electrode pair. The carbon fibers treated with urea at 450℃has the best electric field performances:its potential drift was reduced to about 0. 1 m V/24 h, the self-noise was around 2. 2 n V/rt Hz@1 Hz, and its electrode pair shows a good response to the electric field signal at 1 m Hz, 1 m V.