Three groups of unsaturated red clay samples have been chosen from the three section of in the passenger transportation line respectively. After UU，CU，and CD tests of the samples，the direct shear test target and triaxial test target have been obtained. Meanwhile，after comparing these target with UU test strength index and CD test strength index respectively，the corresponding ratio is obtained and some advice are provided，which has important reference function when it refers to the design parameter in the sector of unsaturated red clay in the passenger transportation line.