The analytical study on the nonlinear phase shift and the change of fundamental wave amplitude caused by Cherenkov cascading second order nonlinearity is given. The result shows that a very large nonlinear phase shift (>π) could be attained by choosing an appropriate reversal period, and a rather large nonlinear phase shift can be attained even if the waveguide does not modulated periodically. The Cherenkov configuration has many advantages such as the large fabrication tolerance, the natural separation of fundamental wave and the SHG wave etc, thus this configuration can be applied to the all-optical switches.