Abstract: This paper introduces the basic calculation method of PWR airborne radioactivity concentration, and analyzes the airborne concentration of noble gases, fission products, corrosion products and tritium during each phase such as normal operation, residual heat removal and RPV opened in terms of relative 1000 MWe PWR’s design experiences. Especially, the detailed calculations are provided in that concerning the phenomenon of increased airborne radioactivity concentration during residual heat removal due to the iodine spike by fuel cladding failure and the corrosion products burst by oxidation operation respectively. Finally, this paper describes some improvement suggestions for internal exposure protection and ventilation design based on the tendency of PWR airborne radioactivity concentration during each phase.