To adapt to the characteristics and service conditions of deep shale oil and shale gas exploitation,the BG125HC high-strength het-erogeneous load resistant casing was developed and its mechanical properties were tested.The results demonstrate that the toughness value of the BG125HC casing remains stable at over 10%yield strength,with a decrease in yield strength of 5.9%at 150℃.Moreover,the col-lapse strength of BG125HC exceeds API standard requirements by 37%,while the shear deformation resistance is 17%higher than that of Q125 grade casing.These findings indicate that BG125HC casing is well-suited for large-scale development of deep shale oil and shale gas.