Yolk-shell nanomaterials with controlled morphology have received great attention because of their promising applications in gas sensing. Here, we reported the facile synthesis of pure and 1-5 mol% Sn doped Co₃O₄yolk-shell nanostructures by calcinating the Co based metal-organic framework (MOF, ZIF-67) prepared from hydrothermal method. The morphologies of the as-obtained samples were characterized by various experimental techniques. Furthermore, the gas sensing properties were systematically measured. Gas sensors based on 3 mol% Sn doped Co₃O₄yolk-shell nanostructures exhibited extremely enhanced response to ethanol at 200℃ (R-g/R-a = 13.4-100 ppm at 200 ℃) and low detection limit (R-g/R-a = 1.3-1 ppm ethanol at 200 ℃). Most importantly, the gas response to 100 ppm ethanol is still maintained well after continuous measurement for 20 days.