There have been various research works in the field of bar straightening in last several decades, but somehow probabilistic approach of various process parameters of bar straightening has practically not been deeply looked into. This paper has made an effort to discuss mainly on probabilistic approach on the estimation of curvature of round bars along with brief narration of bar straightening process. Bar straightening involves various parameters like bar size and speed, helix angle, roller speed, pitch length, bending moments, residual curvatures. Statistical concept has been applied through these parameters to estimate final mean residual curvature of the processed bar.