In this paper, the minimum ignition energy (MIE) for methane in an atmosphere of CO2/O-2 is measured at 0.1-0.7 MPa and 183-273 K using a gas explosion experimental device that is able to withstand a temperature as low as 113 K. Effects of initial temperature (T-0) and initial pressure (P-0) on MIE are studied via experiment and a simple theoretical analysis. Results indicate that in our experimental setup, the sensitive conditions of MIE are an equivalence ratio of 1 and an electrode gap of 1 mm. Under low initial temperature, the trends in MIE with respect to initial pressure and temperature in an atmosphere of CO2/O-2 are similar to those in an atmosphere of N-2/O-2. With an increase in initial pressure and temperature, MIE gradually decreases. MIE has a linear correlation with the reciprocal of the square of the initial pressure and the reciprocal of the initial temperature. At low initial temperature, P-0 has a large impact on MIE, whereas at low initial pressure, MIE is more sensitive to initial temperature. At the same initial temperature and pressure, MIE in an atmosphere of CO2/O-2 is about 1.2 times larger than that in an atmosphere of N-2/O-2 atmosphere. CO2 is more dilute than N-2 in accordance with large heat capacities and small thermal conductivities.