Abstract: Roughing Rolling Works is required by Seamless Steel Works of Baoshan Complex to provide billets with weight tolerances not exceeding ±1% and diameter deviations less than ±1mm. For this reason, PLC is used in Roughing Rolling Works to control pushing and stretching forces of rolling on 6VH mandrel mill with the result of slight pushiag and stretching rolling obtained, therefore billets with various steel grades and with satisfied deviations of weight and diameter over full length can be produced.