Abstract: Taking Chinese listed companies as the research sample and adopting stock price non-synchronicity to measure stock price informativeness, an empirical test was carried out to explore the causal relationship between stock price informativeness and capital allocation efficiency based on the regression models of panel data. The results indicated that a significantly negative relationship exists between price informativeness and corporate overinvestment; in other words, the information exclusive to stock price can inhibit overinvestment and then improve capital allocation efficiency. Moreover, high stock price informativeness can significantly enhance future operating performance. Consequently, stock price informativeness has a positive effect on optimal capital allocation.