Adsorption isotherms of pure CH4, C2H6, CO2, and SO2 are measured on one typical shale sample using the static volumetric method. The adsorption capacity of the above four gases is then compared to elucidate the affinity of each gas species on shale. Nuclear magnetic resonance (NMR) technique is then used to investigate how SO2 and CO2 exert the influence on the adsorbed CH4 and C2H6 on the organic shale. Based on the measured adsorption isotherms, SO2 presents the strongest adsorption capacity among the four gases, and is followed by C2H6, CO2, and CH4. It suggests that SO2 can be served as a potential agent for recovering the heavier hydrocarbon species, i.e., C2H6, from organic shale, while CO2 may be only suitable for the shale CH4 recovery. After introducing CO2 or SO2, based on the variation of T-2 spectrum of the "CH4 or C2H6-saturated" shale sample, we infer that the adsorbed CH4 can be readily replaced by CO2 and SO2 from shale surface. However, the adsorbed C2H6 molecules are less probably replaced by CO2 compared to SO2. In addition, the amount of desorbed CH4 and C2H6 resulted from CO2 is much smaller than that of SO2, suggesting the superiority of SO2 for shale resource recovery. We expect this strategy will inspire new perspectives for the recovery of shale resources using the method of flue-gas treatment.