Mechanism and evolution of the pore-air natu-ral convection cooling effect in fractured-rock embankmentsin permafrost regions are studied using a numerical repre-sentation of the non-dimensional governing equations in variable permeability porous media. The analyses show that winter-time natural convection in fractured-rock embank-ments begins to occur in the side slope portions and gradu-ally develops from the left and right side slope portions to themiddle portion of embankment. The more significant distor-tion of isotherms from their initial orientations due to heat conduction alone is that the cooling effect of winter-time natural convection on the fractured-rock embankment is stronger. The minimum critical Rayleigh numbers triggering natural convection of the pore-air in the side slope portions and the middle portion of embankment were obtained. The factors of influence on triggering winter-time convection cooling effect in fractured-rock embankments were analyzed. Finally, the assertion that the techniques of the frac-tured-rock revetment and berm are the effective measures to maintain the heat stability of the roadbed in permafrost re-gions is theoretically demonstrated. Mechanism and evolution of the pore-air natu-ral convection cooling effect in fractured-rock embankments in permafrost regions are studied using a numerical repre-sentation of the non-dimensional governing equations in variable permeability porous media. The analyzes show that winter-time natural convection in fractured-rock embank-ments begins to occur in the side slope portions and gradu-ally develops from the left and right side slope portions to themiddle portion of embankment. The more significant distor-tion of isotherms from their initial orientations due to heat conduction alone is that the cooling effect of winter-time natural convection on the fractured-rock embankment is stronger. The minimum critical Rayleigh numbers triggering natural convection of the pore-air in the side slope portions and the middle portion of embankment were obtained. factors of influence on triggering winter-time convection cooling effect in fractured-rock embankments were analyzed. Finally, the as sertion that the techniques of the frac-tured-rock revetment and berm are the effective measures to maintain the heat stability of the roadbed in permafrost re-gions is theoretically demonstrated.