Aiming at the working requirements of the automatic bending and obstacle avoidance of the hole detector， an autonomous bending mechanism driven by a two-way shape memory alloy （SMA） wire is designed. The SMA wire actuation characteristic test platform is built， and the driving behavior of SMA wire is systematically analyzed. It is found that the shrinkage rate of the SMA wire with a diameter of 0.5 mm reached 4%， and its load capacity reaches 83.23 N， satisfying the driving requirements of the hole detector bending. In addition， the kinematics model of the bendable hole probe mechanism is established， and the reachable space of the end mounted optical lens is obtained. Furthermore， the control experiment of the mechanism is carried out， and the result shows that the maximum bending angle of the mechanism is 22.3o. The autonomous bending mechanism designed in this paper has practicality.