This paper empirically studies the impact mechanism of the depth of digital trade rules on China’s digital service trade exports and explores the improvement paths for China accordingly. Based on the transaction cost theory and other foundations, this paper systematically classifies rule provisions into four categories: access and facilitation, cross-border data flow, digital intellectual property rights, and privacy protection and data security. It also uses the gravity model of trade to quantitatively analyze 22 Regional Trade Agreements texts involving China. The empirical results show that: the depth of digital trade rules as a whole significantly promotes digital service trade exports; the core driving factors include the gap in digital infrastructure, differences in higher education levels, urbanization levels, and GDP gaps; all four categories of provisions show a significant positive impact, among which access and facilitation provisions have the most prominent promotional effect. Heterogeneity analysis further reveals that the depth of rules has a significantly stronger promotional effect on trade partners in developed countries than in developing countries; sector-specific tests show that the financial services sector benefits the most, while the intellectual property sector is inhibited. Based on this, this paper proposes that China should actively participate in the construction of global rules, improve digital infrastructure, deepen the implementation of provisions, orderly expand opening-up in the digital field, strengthen intellectual property protection to balance innovation incentives and market expansion, and improve laws and regulations to ensure data security.