The MgO-CaO clinkers were prepared by light burnt and calcining Yanfeng dolomite (＜0.088 and ＜0.045 mm), and then were modified via hydration carbonation technology. The synthesis conditions including particle size of the starting materials, the light burnt and calcining temperatures were optimized. The morphology of the modified clinkers surface was observed via SEM, the growth pattern and crystal morphology of the modified layer and the hydration resistance of the clinkers were researched. The results show that: (1) the suitable light burnt temperature is 850 ℃; (2) the suitable calcining temperature is 1 650 ℃; (3) after hydration carbonation, a dense and uniform CaCO3 layer with a certain thickness is formed on the surface of the clinkers; prolonging the modification duration can obviously enhance the hydration resistance of the clinkers; particle size plays an important role in the formation and growth of CaCO3 on the surface.