Abstract: Environment temperature has an important effect on the performances of marine microbial fuel cell (BMFC).A comparison test has been conducted on the performances of the BMFC at 4 ℃ and room temperature (25 ℃).The results show that startup time of anode at 4 ℃ is significantly slower than that at room temperature (25 ℃), while the temperature has no effect on cathode startup time.At room temperature, the cell internal resistance is 703 Ω, but at 4 ℃, is 1005 Ω, increment 302 Ω, meanwhile the maximum output power density and current density at room temperature increases about 10 mW/m² and 46.6mA/m² respectively than that at 4 ℃.The poor performance of BMFC at low temperature may be due to lower microbial activity and mass diffusion velocity at lower temperature.This experiment provides guidance for design of BMFC and is practically significant for application.