Abstract: Combined gas drainage from surface and underground is an important mode of gas control in deep coal mines in China. Clarification of the synergistic mechanism of combined gas drainage from surface and underground and quantitative evaluation of its control effectiveness are of substantial practical and scientific significance for achieving low-cost and long-term control of gas emissions from mining areas. A typical deep working face adopting combined gas drainage from surface and underground is taken as the engineering case. Numerical simulation is combined with comparative analysis of field gas drainage data to investigate the characteristics of mining-induced overburden failure and gas migration patterns. Based on the attenuation characteristics of gas pressure and volume fraction, the effective gas drainage radius of the ground well is determined, and the optimal location of the ground well is identified. In addition, the gas drainage effects of the high-level drainage roadway, highly-located directional holes, and the ground well are compared, and their respective roles in overall gas control in the goaf and local gas control at the upper corner of the working face are systematically evaluated. The results show that the gas volume fraction and airflow distribution in the goaf are significantly altered by gas drainage through the ground well. When the distance between the wellhead and the working face exceeds 55 m, the gas volume fraction in the upper part of the goaf near the working face increases rapidly from below 10%, indicating that the effective gas drainage radius of the ground well is approximately 55 m. Under the investigated conditions, the optimal location of the ground well is determined to be 40 m from the air return way and 40 m above the coal seam roof, at which a pure quantity of gas drainage of 7.62 m³/min is achieved. The gas volume fraction at the upper corner is significantly reduced by the high-level drainage roadway and highly-located directional holes, although their effective control ranges are limited. The overall gas distribution in the goaf is substantially improved by gas drainage through the ground well; however, when the ground well is used alone, a risk of the gas volume fraction exceeding the allowable limit at the upper corner remains. With the combined gas drainage scheme of a “ground well + highly-located directional holes along the strike,” the gas volume fractions in both the goaf and the upper corner are reduced by more than 80%, and those at all monitoring points are maintained below 0.25%. Thus, both overall gas control in the goaf and local gas control at the upper corner are achieved. Theoretical support and practical guidance are provided for the exploration and development of combined gas drainage from surface and underground in deep coal mines in China.