The upheaval deformation of micro-swelling mudstone subgrade presents a significant challenge in the development of high-speed railways. In order to fabricate similar materials suitable for conducting model experiments on high-speed micro-swelling mudstone subgrades, bentonite was incorporated as a modifier in a barite-sand-cement composite, considering the properties of the field prototype mudstone. Orthogonal testing and range analysis were utilized to assess the influence of each ratio factor on the swelling characteristic parameters and strength parameters of the material. A linear regression analysis was performed on the parameters and primary influencing factors to ascertain the range of material ratios. Based on the above results, an appropriate ratio of similar materials was established via a trial mix test. Subsequently, the validity of this ratio was confirmed through the implementation of a water absorption disintegration test and a swelling deformation test. The findings suggest that each material parameter exhibits the highest sensitivity to the bentonite content, demonstrating a positive correlation. The swelling characteristic parameters demonstrate a positive correlation with the barite powder content and a negative correlation with the gypsum content. The strength parameters demonstrate a positive correlation with the gypsum content. The internal friction angle is predominantly adversely affected by the presence of barite powder. The influence of various factors on the properties of similar materials is apparent. It is beneficial to replicate the micro-swelling characteristics of mudstone with different parameters by modifying the material composition in experimental investigations. The physical and mechanical properties, water absorption, disintegration, softening, and swelling properties of the specified material proportion closely resemble those of mudstone. The aforementioned characteristics satisfactorily meet the criteria for performing physical model tests on mudstone subgrades in high-speed railway applications. The research findings provide substantial evidence to support the effective prevention and management of upheaval deformation issues in the foundation of the southwest high-speed railway.