Abstract: The accelerated neutral salt spray aging test was used to simulate the marine atmospheric environment, and the flexural properties of glass fiber/unsaturated polyester composites in salt spray environment were investigated. Through changes in moisture absorption rate, glass transition temperature, Barcol hardness and bending properties of glass fiber/unsaturated polyester composites after salt spray acceleration aging, in addition with the corrosion depths obtained by metallographic microscope, the effects of corrosion depth on durability of glass fiber/unsaturated polyester composites were studied. The results indicate that the moisture absorption of glass fiber/unsaturated polyester composites increases quickly with time in the early aging stage, and tends to be stable at last. Glass transition temperature of glass fiber/unsaturated polyester composites firstly increases, then decreases. After 180 d of aging time, the glass transition temperature increases by 2.1%. After 180 d of aging time, the Barcol hardness decreases by 17.6% compared to the un-aged one and flexural strengths loss rate is 10%. Based on the corrosion depths obtained by metallographic microscope analysis, the relationship between the corrosion depths and flexural strength was established for glass fiber/unsaturated polyester composites.