Economic policy uncertainty is a key determinant of exchange rate stability. This study investigates the impact of China's categorical economic policy uncertainties on the long-term correlation between onshore (CNY) and offshore (CNH) Renminbi (RMB) exchange rates. We find that fiscal policy uncertainty (FPU), monetary policy uncertainty (MPU), and exchange rate and capital account uncertainty (EXRPU) have a significant negative effect on this correlation, while trade policy uncertainty (TPU) has no significant impact. Furthermore, CNY and CNH do not effectively diversify risks and provide only limited hedging benefits.