This paper constructs a DID model using the exogenous shock of the implementation of the new Budget Law in 2015, based on data from listed companies from 2009 to 2022, it founds that fiscal transparency significantly reduces executive compensation, increases ordinary employee compensation, and ultimately reduces the pay gap within enterprises, supporting that openness can lead to fairness. Mechanism tests show that constraining corporate rent-seeking behavior, reducing corporate risk-taking, and alleviating corporate financing constraints are three core mechanisms through which fiscal transparency reduces the pay gap within enterprises. Heterogeneity studies confirm that the pay governance effect of fiscal transparency is more pronounced in enterprises with lower bargaining power among employees, poorer internal controls, and non-state-owned enterprises. Further analysis reveals that the narrowing effect of fiscal transparency on the pay gap within enterprises mainly stems from reducing unreasonable excess pay gaps, with no impact on reasonable pay gaps that can bring positive incentives. At the same time, it shows a clear "helping in times of need" characteristic. This study not only reveals the micro-mechanism of the close relationship between openness and fairness, but also has important implications for the government to optimize the income distribution pattern.