Abstract: In order to research the mechanical properties of red sandstone under negative temperatures, we need a large number of tests on negative temperature triaxial compression.But the existing test efficiency can not meet the needs of large-scale trials. Concerning the long test period and low efficiency of the testing machine found during the experiment, the author improved the testing machine in the following aspects: (1) Abandon the original oil storage barrel and infuse the pre-chilled aviation silicone oil into the pressure chamber through oil pump to reduce the cooling time of aviation silicone oil in the pressure chamber. (2) Change the way of lifting from rigid connection to soft connection by chains to reduce the frequency of lifting and lowering. The testing machine’s cooling rate was improved and the test period was shortened after changing those conditions. The period of first completed test was shortened from 7 hours to 4 hours while the period of one follow-up test was shortened from 2 hours to 50 minutes, which doubled the efficiency, achieving testing multiple samples in one day. Meanwhile, changing the way of connection improved security.

Key words: low-temperature triaxial testing machine, improvement of equipment, triaxial compression test, velocity of cooling down