We perform N³LO QCD analysis of the world data on the unpolarized DIS structure functions to determine \alpha _s and valance quark distributions with fully correlated errors. Due to increasing the accuracy of DIS experiments and reduction the experimental errors on determining the strong coupling constant, the higher order analysis is required. The Padé approximations are used to estimate the 4-loop anomalous dimension. We consider the non-singlet sector of parton distributions in our calculations. A comparison of the N³LO/N²LO with N³LO/NLO ratios for up and down valence quark distributions indicate outstanding influence of the higher order analysis.

PACS numbers: 13.60.Hb, 12.39.–x, 14.65.Bt