Abstract: Coastal engineering projects such as offshore tunnels and shafts are surrounded by rock masses that are constantly exposed to seawater corrosion. This will lead to the degradation of the rock and soil properties, thereby threatening the long-term stability and safety of the projects. Existing studies mostly focus on the qualitative description of rock body indicators after corrosion or the quantitative analysis of specific factors, lacking a quantitative evaluation system for the comprehensive performance of the rock mass under the combined effect of multiple factors. To address this limitation, this paper uses multiple key parameters such as the longitudinal wave velocity, uniaxial compressive strength, triaxial compressive strength, and mass loss rate of the rock body after chemical corrosion as evaluation indicators, and constructs a comprehensive quantitative evaluation system. The CRITIC method is used to objectively determine the weight distribution, and finally the corrosion degree is quantified in a percentage-based scoring system, allowing for a direct comparison of the corrosion conditions of different samples. The research results show that the performance of the samples changes the most under acidic conditions (pH=2), with the most significant quality loss. The slope of the longitudinal wave velocity decrease is as high as −11.65. The comprehensive evaluation score of the S1 sample in this corrosion environment reaches 100; while under neutral conditions (pH=7), the performance change of the samples is the least, and the score of the S9 sample in this environment is only 2.52.This system not only improves the accuracy and practicality of corrosion evaluation but also provides data support and theoretical basis for the durability design and safe operation of related coastal projects, and has important reference significance for dealing with corrosion conditions of coastal and offshore projects.