Ethane dehydrogenation (EDH) to produce ethylene requires high operating temperature to achieve satisfactory ethylene yield, however, this process leads to coke formation and catalyst deactivation. Here, an active site isolation strategy was employed to inhibit side reaction and coke formation over fifteen types of metal single-atom metal/graphitic carbon nitride (M/g-C₃N₄) catalysts. Density functional theory (DFT) calculations completely describe reaction network of ethane dehydrogenation. On-lattice kinetic Monte Carlo simulations were carried out to evaluate catalytic performance under the realistic conditions. The Co/g-C₃N₄, Rh/g-C₃N₄, and Ni/g-C₃N₄ catalysts were screened out to exhibit higher C₂H₄(g) formation activity and C₂H₄(g) selectivity close to or equal to 100%. The low reactant partial pressure 0%–5% at atmospheric pressure facilitates ethane dehydrogenation, and the appropriate temperatures over Co/g-C₃N₄, Rh/g-C₃N₄, and Ni/g-C₃N₄ catalysts are 673.15, 723.15, and 723.15 K, respectively. Especially, Co/g-C₃N₄ catalyst presents the highest C₂H₄(g) formation activity, attributing to the appropriate anti-bonding strength between C atom and metal single-atom. Further, a simple descriptor, the reaction energy of C₂H₅^* dehydrogenation to C₂H₄^*, was proposed to quantitatively and quickly evaluate C₂H₄(g) formation activity. The present study laid a solid foundation for efficient design and development of single-atom catalysts with high-performance for selective dehydrogenation of alkanes.