Based on the financing motivation of equity pledges, this study explores whether and how monetary policy adjustment affects the stock pledge behaviour of listed companies. The empirical findings show that monetary policy adjustments significantly affect the stock pledge of listed companies; that is, a tightening monetary policy increases the stock pledge phenomenon of listed companies, and an expansionary monetary policy reduces the stock pledge phenomenon. Heterogeneity analysis revealed that monetary policy had a greater impact on the stock pledges of non-state-owned enterprises, enterprises with weak government–enterprise relationships and enterprises without bank–enterprise relationship. The results of mechanism tests suggested that a quantitative monetary policy only affects the stock pledge behaviour of listed companies through financing costs and that a price-based monetary policy affects the stock pledge behaviour of listed companies through financing costs and financing scale. This article expands the literature on the impact of monetary policies on equity pledges and enriches studies on macroeconomic policies and microfirm behaviour.