The turbulence driven by ion temperature gradient,mass flow shear,parallel to the magnetic field,and the impurity ion density gradient in plasmas with multiple ion species is studied in a sheared slab magnetic configuration.The particle diffusion induced by the turbulence is obtained with quasi-linear fluid theory.The possible inward ‘pinch' of the majority ions and the inward flow of the impurity ions,depending on plasma parameters,are both calculated,and the corresponding diffusion coefficients are given.It is shown that the increase of parallel velocity shear may have benificial effects on plasma confinement.The correlations with Tokamak experimental observations are discussed.