The corrosion of the fluid to the pipes could damage the pipe structure, and then affect the safe operation of the whole pipeline system in the nuclear power plant. In order to assess the influence of the corrosion flaws on pipe integrity, it is necessary to perform the stress analysis and calculate the remaining strength of the pipes containing flaws. In this paper, the corrosion flaws in the seawater cooling pipes are considered as the volumetric type flaws. The remaining strength of the pipes containing the flaws has been calculated, the minimum required wall thickness of the pipes has been obtained, and the flaws have been assessed according to SY/T 6477 Standard. The finite element method has been used to analyze the pipes containing corrosion flaws. Stress distribution of the pipes has been obtained under the pressure and nozzle loading. Based on the RCC-M Standard, the strength assessment has been conducted. Results showed that the stress calculated from SY/T 6477 Standard is close to that from the finite element method, and it can be considered that the assessment method summarized from SY/T 6477 Standard is suitable for the current pipes containing flaws under the nozzle loadings. Therefore, this method can be used to assess the corrosion flaws of the seawater cooling pipes rapidly, and provide advices for the monitoring and repair of the pipes containing flaws in nuclear power plants.