The carbonation resistance of ready-mixed concrete in Qinhuangdao was investigated and the predicted experimental data indicated that the carbonation resistance of concrete in Qinhuangdao was unsatisfactory. The longest predicted service period of concretes in this survey is merely 39.1 years when the carbonation depth reaches 25 mm; and the shortest is only 8.7 years. It’s awfully difficult to guarantee the durability of reinforced concrete structures for 50 years. The experiment results also shows that both the water to binder ratio and the mineral admixture mass fraction have great influence on the carbonation resistance of concrete. With the decrease of water to binder ratio and mineral admixture mass fraction, the predicted service years of ready-mixed concrete increase dramatically.