Non-singlet structure function in the NNLO approximation

We use recently the next-to-next-to-leading order (NNLO) contributions to anomalous dimension which is governing the evolution of non-singlet quark distributions. The xF3 data of the CCFR collaboration is used to parameterize the non-singlet parton distributions in higher order. In the fitting procedure, Bernstein polynomial method is employed. The results of valence quark distributions in the LO, NLO and NNLO are compered with different theoretical models.