Objective: To analyze the dynamic spectral characteristics of patients with early spasmodic dysphonia (SD) and its value in evaluating clinical prognosis. Methods: 65 patients diagnosed with early SD in our hospital were collected from January 2022 to January 2024. All patients were divided into two groups, that were effective group (n=58) and ineffective group (n=7). The indexes of the dynamic frequency spectrum characteristics, voice handicap index (VHI-30) and modified French articulation disorder assessment (mFDA) were measured at pre- and post-therapy and compared between two groups. The risk degrees of the clinical indexes to the clinical effect in patients with SD were analyzed by multivariate Logistic regression analysis. The diagnostic values of the clinical indexes to the prognosis in patients with SD were analyzed by receiver operating characteristic curves (ROC). Results: Compared to pre-therapy, the indexes of shimmer, jitter, total time spent on reading standardized paragraphs, and the number of voice interruptions at post-therapy in 2 groups were lower (P<0.05), and the indexes of DSI, MPT, and sound intensity range at post-therapy in 2 groups were higher (P<0.05). Compared to ineffective group, the index of the proportion of moderate and severe symptoms in the effective group was lower (P<0.05), and the indexes of shimmer and jitter at pre-therapy in the effective group was lower (P<0.05), but the DSI, MPT, and sound intensity range in the effective group was higher (P<0.05). Multivariate logistic regression showed that the severity of spasms DSI, and range of sound intensity before treatment were important indicators for predicting clinical efficacy (P<0.05).Receiver operating characteristic (ROC) curve showed that area under curve (AUC) of DSI and sound intensity range for predicting clinical efficacy were 0.853 and 0.815, respectively (P<0.05). Conclusion: The dynamic spectral characteristics and quantitative parameters of early SD patients have important value for disease diagnosis and evaluation of clinical efficacy.