Particle-in-cell (PIC) simulations are used to study the nonlinear process of stimulated Raman scattering (SRS) excited by a rotated polarized laser interacting with underdense plasmas. The influence of the rotating frequency on linear SRS growth rate is theoretically analyzed and the long-term nonlinear SRS behavior excited by the rotated polarized pump is illustrated by the PIC simulations. Our results show that the evolution of reflectivity, plasma wave and electron energy distribution in the nonlinear stage is quite different from that in the linear stage, which is principally caused by the mitigation of electron trapping. Furthermore, our fluid theory and simulations have demonstrated that opposite to the suppression of Raman backscattering, Raman forward scattering becomes stronger with increasing rotating frequency. The above nonlinear effects are valid in the regime of and a plasma length of hundreds of microns for the key role of the kinetic effect.