Abstract: On the basis of the former rheological testing equipment, a new tri -axial rheological rock testing machine with high pressure confinement, which is financially supported by a scheme for equipment upgrade and renovation from the Ministry of Science and Technology, and characterized with the capacities of stable testing pressure servo -control and an automatic acquisition, has been manufactured recently. This paper presents some technical renovations , verifications for its performances, and some rheological results achieved by actual tests for limestone samples with the new machine. The advanced techniques, combined with servo -control, ball screw and hydraulic operations, have been employed for testing pressure regulation system of the newly developed equipment,which shows a good performance for its pressure stabilizing control during rheological test. 