Under long-term loading from aircraft, the cumulative deformation of airport subgrade filled with saline silt in northwest China can be a key factor that affects the service performance of the airport. Taking the silt in a typical area of northern China as example, the dynamic triaxial test was carried out to investigate the influence of salt content (mass fraction) on the dynamic characteristics of silt under cyclic loading. A cumulative plastic strain of 4% was selected as the failure strain based on the test results, and a prediction model of dynamic strength of salinized silt was proposed. Results show that with the increase in dynamic stress amplitude, the plastic deformation of salinized silt gradually changed from plastic stability to incremental failure. The salt content largely affected the cumulative axial strain, dynamic modulus, and critical dynamic stress of silt. At the same dynamic stress amplitude, as the salt content increased from 0 to 5%, the cumulative axial strain decreased firstly and then increased at the salt content of 1%. At low dynamic stress amplitude, the dynamic modulus decreased with the increase in salt content. The strength of salinized silt experienced a short growth at 1% salt content and a gradual attenuation at high salt content, which might be explained from a microscopic view that the strength of salinized silt sample was closely related to the ion concentration in the soil pores and the arrangement of soil particles. According to the dynamic strength prediction model, the critical dynamic stress for the silt with 1% salt content was about 2.2 times that of silt with 5% salt content. The conclusions of the study can provide reference for the airport runway design and construction in saline silt area.