It is known to all that the Moran measure \(\mu _{\rho ,\{D_n\}}\) can be expressed as \(\begin{aligned} \mu _{\rho ,\{D_n\}}=\delta _{\rho D_1}*\delta _{\rho ^2 D_2}*\delta _{\rho ^3 D_3}*\cdots \end{aligned}\) in the sense of weak convergence. We prove that \(\rho ^{-1} \in \mathbb {N}\) when \(\mu _{\rho ,\{D_n\}}\) is a spectral measure under the conditions \(\mathcal {Z}(\widehat{\delta }_{D_n}) \subseteq \alpha _n \mathbb {Z}\) for all \(n \in \mathbb {N}^{+}\) . And we provided an example to explain this phenomenon.