The chloride ingress of prestressed concrete should consider much more factors than common reinforced concrete. And the prestressed concrete covering layer system is a complex system which includes not only the non-uniform layer of concrete, but also the non-prestressed reinforcement, the metal corrugated pipe and the cement paste incrustation body in the pipe. Taking into consideration of the effect of stress level in concrete and the non-prestressed reinforcement, the multi-factors for chloride ingress corrosion model is achieved and the durability limit state equation for prestressed concrete structures is established. The paper presents a determination method for the depth of the covering layer system of prestressed concrete structure in marine environment. The principle for zonation of the prestressed concrete covering layer system’s minimum depth is established after sensitivity analysis of the effect factors in the marine environment, and the environment temperature and humidity are identified as the main environment sensitivity factors for the depth. Therefore, the paper also proposes zoning method and the division regions for the prestressed concrete covering layer system depth of the coastal region in China.