In comparison with oil-based cracking technologies, the on-purpose dehydrogenation of propane (PDH) is a more eco-friendly and profitable approach to produce propylene. However, the prevalent industrial PDH catalyst, Pt-Sn, suffers from not only the high costs of Pt, but also fast deactivation triggered by sintering of Pt species. Thus, the development of more cost-efficient PDH catalysts with satisfactory stability and propylene selectivity has been a major focus of interests in the community of materials science. By means of density functional theory (DFT) calculations, the present work reveals that single vanadium (V) atom anchored on graphitic carbon nitride (V1/g-C3N4) may serve as a promising single-atom-catalyst for non-oxidative PDH with industrially practical activity, selectivity and thermal stability. The high activity of V1/g-C3N4 for PDH is attributed to the low-coordinated 3d orbitals of single V atoms, while the propylene selectivity is originated from the inhibition of di-σ binding mode of propylene on the single V atoms. This work provides a guideline to design and screen out promising single-atom catalysts for selective dehydrogenation of alkanes.