Durability of concrete structures in marine engineering around Bohai Gulf was studied. According to the data obtained from a great series of experiments， the effect of mix design factors including different types of supplementary cementitious materials and different water-binder ratios on the life span of concrete structure in marine environment was carefully studied with the help of ChaDuraLife V1.0 life prediction model and software， which is developed on the base of reliability and modified chloride diffusion theory. The results show that the reduction in the water-binder ratio and the increment in content of fly ash and ground slag can effectively prolong the expected life span of marine concrete structures. Taking the concrete structure with the steel cover thickness of 75 mm in sea splash zone around Bohai Gulf as an example， the mix design which has the water-binder ratio of 0.30， fly ash content of 20% and slag content of 40% is corresponding to the longest life span of marine concrete. In this area，the minimum thickness of concrete steel reinforcement in this mix design corresponds to the life span of 100， 200， 500 a are 60， 75， 120 mm respectively.