Abstract: Red beds were distributed extensively in the southwest,northwest,central south and southeast of China.Using ZSS50 cyclic load equipment experimental studies on dynamic performance of red mudstone subgrade of Dazhou-Chengdu Railway were made to study the applicability of red mudstone for filling embankment and subgrade bed,and further to expand the application of red mudstone in subgrade engineering based on the physical and mechanical characteristics of red mudstone.The dynamic performance and deformation performance of red mudstone subgrade bed were analyzed under different cyclic loads with and without influences of rainfall.It was indicated that all the dynamic indices and residual settlement of red mudstone subgrade met the design requirements,and red mudstone could be used to fill the embankment and subgrade bed of passenger lines or mixed passenger and freight railways.