This paper investigates the effects of mixed-ownership reform (MOR) on tone management (ABT) in the management discussion and analysis (MD&A) disclosures of Chinese state-owned enterprises (SOEs). Using a FinBERT-based natural language process (NLP) model, we document a significant negative association between MOR and ABT. Financial constraints serve as an important transmission channel: as MOR increases financial constraints and reduces managers’ incentives for tone manipulation. The effect is moderated by financial reporting quality: it is stronger when reporting quality is poor and weaker under higher conservatism. Heterogeneity analyses show stronger effects among SOEs in less developed regions, firms with aggressive earnings practices, and those with limited analyst coverage. The results highlight how MOR reshapes managerial disclosure behaviour and the information environment of SOEs.