The rig column is an important load-bearing part of downhole equipment. Its performance directly affects the safety and reliability of the whole vehicle. By establishing the three-dimensional model of the column， the mechanical analysis and finite element analysis of the column of ZDY12000LD directional drilling machine are carried out， and the strength of the column is checked under the maximum lifting force. The mechanical properties of the column are significantly improved by replacing the original column material Q345 steel with Q550 steel. The bending stress of the column is increased by 43%， the deformation is reduced by 4%， the bearing capacity and safety reliability are significantly improved， and the stability， safety and reliability of the rig operation are enhanced.