Abstract: Based on analysis of tube deformation-loading during straightening of steel tube with the 6-high straightener and consideration about how to improve it,the roll-pair flatening,o-val-straightening process with the said machine is proposed. It is concluded that proper setting of roll space and the mounting angle of the roll is a very important approach to improving straightening accuracy,while proper setting of the bending-straigntening screwdown force of the intermidiate roll is critical to all-round improvement of steel tube straightening quality.