This paper presents a new dither adding method for multistage-noise-shaping (MASH) digital delta-sigma modulator (DDSM), to reduce the output spurious tones. In this method, the additive dither signal is added to two different nodes of any preceding stage of the MASH DDSM, without using dither shaping filter. Then, those dither signals are sent to the error cancellation logic (ECL), where they are eliminated by each other, avoiding appearing in the output spectrum. Simulation results show that, for the MASH DDSM, the new dither adding method can guarantee a spur-free spectrum for all digital constant inputs without raising the noise floor.