Abstract: Ultra-deep (>6000 m) Cambrian dolomite is a typical formation encountered in China’s ten-thousand-meter drilling operations, and its coupled thermo-mechanical behavior directly governs borehole stability and efficient rock breaking. To reveal the mechanical characteristics and thermally induced damage mechanism of this rock, ultra-deep Cambrian dolomite samples from the Tarim Basin were tested under high-temperature high-pressure triaxial compression at temperatures of 25-160 ℃ and confining pressures of 0-100 MPa. A finite-discrete element thermo-mechanical model considering mineral heterogeneity was established and calibrated against the tests, then used to predict behavior over a wider temperature-pressure range. The tests show that the dolomite exhibits high strength and high residual strength, with strength increasing markedly with confining pressure and elastic modulus decreasing with temperature, while the failure mode shifts from axial splitting to shear sliding. The simulations predict that thermally induced microcracks are predominantly tensile and initiate preferentially at dolomite-quartz interfaces with the largest thermal expansion mismatch. A temperature-confining pressure coupling coefficient is introduced to quantify the compensation of confining pressure for high-temperature strength loss, providing a tool for in-situ strength prediction. The results offer theoretical support for borehole stability control and efficient rock breaking in ultra-deep carbonate drilling.