We deduced the analytical expression of the time-resolved energy spectrum density for shaped pulse stacked by 2M chirped Gaussian pulse using wavelet transform and complex Morlet function. Time-resolved power and instantaneous central wavelength distribution of the stacking chirped Gaussian pulse have been obtained through wavelet transform. It’s found that the power oscillates in the time domain, and the instantaneous central wavelength jumps when the power is zero. Increasing the chirp will aggravate the power oscillation and the instantaneous central wavelength jump. The instantaneous central wavelength jump occurs only when the power is zero. Therefore, the pulse energy remains in the wavelength range determined by the chirp of fundamental pulse. Simulating results also show that a little change of the pulse overlap factor will greatly influence the packing ratio and the flatness of the shaped pulse, both of those cannot simultaneously reach optimum. Therefore, the pulse overlap factor should be selected eclectically.