We investigate the electron dynamic process of periodic nano ripples formation on fused silica induced by temporally shaped femtosecond laser. The dynamic model for predictions of ripple period is proposed by introducing the mechanisms of non-linear ionization and surface plasmon polaritons (SPPs) interaction. The quantitative relation between nano ripple period and temporally shaped pulse separation is obtained by using the proposed model. It is revealed that the nano ripple period can be manipulated by adjusting the temporal intervals of the temporally shaped pulses due to the transient adjustment of the wavevector matching process during ripple formation via temporally shaped pulses. The theoretical predictions of the ripple period match well with the experimental data. This study provides the fundamental understanding of transient formation mechanism of ripples, and the precise manipulating of ripple period.