For the case of pulse shaping by the usual pulse stacking scheme, the beat effect brings intensity fluctuation to the shaped pulse, and the spectrum interference effect will cause intensity fluctuation of the spectrum of the shaped pulse. To solve these problems, a pulse stacking scheme based on the wavelength division multiplexing (WDM) is proposed. Theoretical analysis and numerical simulation are developed on this scheme and this scheme is compared with the usual pulse stacking scheme. The results show that the pulse stacking scheme based on WDM can reduce the beat effect effectively, and smoother shaped pulse can be obtained. The larger the wavelength spacings are, the smoother shaped pulse we can get. Otherwise, this scheme can also reduce or eliminate the spectrum interference effect.