Abstract: Some coal mines in our country experience high concentration CO accumulation in the upper corner during regular operations, but this phenomenon is frequently accompanied by no visible signs of spontaneous combustion in the working face.This makes it difficult to monitor and warn of coal spontaneous combustion, which threatens mine production safety.Using Yangchangwan Coal Mine as an example, the CO produced by coal crushing was tested, the original CO in the coal seam was measured and the content of CO in goaf was measured.It was discovered that the coal body adsorbed CO,but the coal seam did not have the temperature and pressure required for gas desorption, indicating that the detected CO may not exist in the coal body.It is concluded that CO gas can be produced in the process of coal crushing even in nitrogen environment and it had a more significant impact on the CO concentration in the upper corner, which was the main source of CO produced in the corner of the working face, and the CO concentration increases with increasing distance from the coal wall.A CO migration and accumulation model of the working face was constructed using Fluent numerical simulation.It was demonstrated that the simulation results were consistent with the field measured conditions by comparing them with the data collected in the field.This information may be utilized to investigate the migration and accumulation law of CO in the goaf of working face.The simulation indicated that the distribution of CO in the goaf was essentially fan-shaped, with the upper corner and end support serving as its centers, along the direction of the working face, the concentration of CO at the goaf's return air side first rises and then falls, while the concentration of CO accumulation was higher.