Abstract: It is important to study the stress deformation and stability of foundation by accurately testing the strength index of soils. For the triaxial tests under low confining pressures (less than 100 kPa), the influences of the piston friction and the rubber membrane can not be ignored. At the same time, the test accuracy and measuring range of equipments are also the important factors that should be considered. This study attempts to explore the influences of factors such as the piston friction and the rubber membrane on the test results by carrying out unconfined compressive strength tests under different conditions and triaxial consolidated undrained shear tests of different equipments, and to explore how to measure the compressive and shear strengths of samples according to the existing test conditions, so as to provide reliable data for design, construction and numerical calculation. In view of the shortcomings of domestic triaxial test equipments, reasonable suggestions are put forward, and it is expected that the triaxial test equipments should be further transformed and upgraded from mechanical manufacturing so as to promote the researches and development of precise triaxial test equipments in China.