To explore the problem of CO concentration overrun in fully mechanized caving faces, a multiphysical field coupling model of CO emission regularity was established in this study based on the gas flow theory, gas concentration field theory, and heat transfer theory. Taking the 014N1−1 working face of the No. 1 coal seam in Ruian coal mine as the research object, the model was applied to simulate the CO concentration in the fully mechanized caving face. The simulation results were found to be consistent with the field detection results. Based on the simulation results, the effects of advancing speed and wind velocity on the CO emissions in the gob and the CO concentration distribution in the working face were analyzed. The results showed that, the lower the wind velocity, the greater the CO emissions. With increasing advancing speed, the CO emissions in the gob first increased, reached maximum, and then decreased. The production conditions were found to be most suitable when the advancing speed and wind velocity were 2 and 1.8 m/s, respectively. Moreover, the CO emission characteristics of the fully mechanized caving face under the conditions of periodic roof weighting, production process, and atmospheric pressure change were monitored and analyzed. We verified the presence of CO in the coal seam and its emission with the progress of coal seam mining. Our results will be useful in the research and analysis of CO emission source, emission regularity, and overrun warning in fully mechanized working faces.