Based on existing research on diversification and corporate performance, a study was conducted on how corporate digital transformation changes the impact of diversity on performance. Using the data of Chinese A-share listed companies from 2007 to 2020, the panel binary selection model, the fuzzy differences-in-differences model and the panel fixed effect model were used for empirical testing, and the traditional multi-period difference-in-differences model was used for comparison. It turns out that there is a strong synergy between digital transformation and diversification. In fact, digital transformation can increase the prob-ability of enterprises to carry out diversification strategy, and improve the level of enterprise diversification. In terms of mechanism, digital transformation can improve the expected benefits of diversification, and this effect is most significant in labor-intensive industries. This study comprehensively uses the theories of asset specificity and scope economy to explore the linkage effect between digital transformation and diversification, creates a new research perspective on the impact of diversification on corporate performance.