Abstract: The holes of the whole stand of the 20-high mill are complex, the processing depth is long and the precision is high. It is necessary to use special processing equipment to complete the holes processing.In view of the characteristics of holes in the whole stand, a boring head for the frame boring machine of 20-high rolling mill is designed.It successfully solves the problems of excessive hole size, excessive hole linearity and parallelism, low inner hole roughness and unstable hole system processing accuracy, which are easy to occur in the processing of non-circular deep hole system.