TSZ - 6A type strain control in three triaxial apparatus according to GB/T50123-1999 "soil test method standard of design and manufacture, used for determining soil samples in equal strain add lotus mode of soil shear strength and deformation characteristics and gap water pressure. This instrument can undertake UU, CU and CD etc shear tests. Strain control mode by single-chip microcomputer control, realize stepless speed, Around pressure and backpressure by single-chip microcomputer automatic control. This machine is easy to operate, compact structure, etc.