The hetero-homogeneous processes, especially, the oxidations ofmethane, ethane and ethylene in gas-phase and in the presence of catalystswere studied. The main factors in oxidative coupling of methane were classi-fied into two types according to their effects on the reactions. The inherent lim-it of the Cyield was discussed from the reaction condition point of view. Aview toward the inherent limit, i. e., a way to avoid the inherent limit by oper-ating at high selectivity, high Cconcentration, efficient product separation andmethane circulating operation, was proposed. The methods to enhance theCselectivity and the Cconcentration in the exit gas, and the method for effi-cient product separation were investigated. In the simulation experiment a prod-uct gas with Cconcentration of 90 (v/v)%, and Cselectivity of 85% (basedon carbon number), was produced under the reaction conditions of 10(at)%aO/SrO catalyst, T=800℃, τ=0.012g·s·cm, P/Po=9, Po=10kPa and atmospheric pressure.