With the continuous deepening of supplyside structural reform, the reform of labor factors has received extensive attention, and how to effectively improve the efficiency of corporate labor investment is particularly important. Based on the sample of central enterprises and their subordinate listed companies from 2008 to 2018, this paper examines the impact of state audit on firms labor investment efficiency. It is found that state audit can significantly improve firms labor investment efficiency; the mechanism tests show that state audit can promote labor investment efficiency by reducing the information asymmetry and agency cost of stateowned enterprises. Further analyses suggest that the positive effect of state audit on labor investment efficiency is more pronounced for firms with higher internal control quality, firms with better external audit quality, firms with higher levels of product market competition, and those belonging to regulated industries, indicating that state audit and various internal and external governance mechanisms of firms can effectively produce synergistic governance effects.