Due to the large external diameter of mechanical power cables, it is difficult to transport and lay them, and the requirement for turning radius of power cables is stricter. In the construction of power cable, if the turning angle is too large, it may cause mechanical damage inside the conductor, and the mechanical damage will be reduced by the insulation strength of the cable until the failure occurs. A cable head fault is found in the construction. When the cable head is made, the length of the three cable heads is the same, and the connection with the equipment is limited by the terrain. The middle-phase cable head grows into an arch and discharges at the root of the cable head. After that, measures should be taken to shorten the connection length of the middle-phase cable head properly so that the three-phase cable head can not be subjected to external forces. Practice has proved that the operation effect is good. It can be seen that in the process of cable construction, the torsion of the cable should be reduced as much as possible. When the cable is turning and remaining, the cable should be in natural bending and the phenomenon of internal mechanical damage should be eliminated.