Liangshui Tunnel of Lanzhou-Chongqing railway and Tianpingshan Tunnel of Guiyang-Guangzhou railway are the background work. Combining the construction process mechanics of soft rock, uniaxial compressive test, Brazilian test and direct shear test under different material proportion are carried out. After comparing and analyzing the basic physical and mechanical parameters of original rock and model materials, the similar materials for soft rock tunnel are attained. The effect of component proportion on material properties is analyzed. These results provide reliable material guarantee for model test of construction process mechanics in soft rock tunnels.