Abstract: In order to study the mechanical properties of similar materials of collapsible loess, orthogonal experiment was used to make up similar material with different proportions which using river sand and barite powder as aggregate, clay and gypsum as cementing material, and diatomite as adjusting material. Research methods such as range analysis and similar simulation were used to study the mechanical properties of similar material. The results show that: 1) The influence of various factors on the collapsibility coefficient of similar materials in descending order is the diatomite mass fraction, moisture content, bone-to-glue ratio, clay-to-gypsum ratio, mass fraction of barite powder; the influence on cohesion in descending order is moisture content, bone-to-glue ratio, diatomite mass fraction, clay-to-gypsum ratio, mass fraction of barite powder; the influence on the internal friction angle in descending order is bone-to-glue ratio, moisture content, diatomite mass fraction, mass fraction of barite powder, clay-to-gypsum ratio. 2) The collapsibility coefficient and cohesive force of similar materials are positively correlated with the diatomite mass fraction, and negatively correlated with the bone-to-glue ratio; the internal friction angle is positively correlated with the bone-to-glue ratio, and negatively correlated with the moisture content. Engineering application shows that the deviation between the experimental value and the theoretical value of collapsibility coefficient, cohesion and internal friction angle is 5.6%, 6.3% and 5.3%, respectively, and the coincidence degree is high; the similar simulation test results are basically consistent with the on-site measured results.