This study applies a time-varying parameter/stochastic volatility vector autoregression (TVP-SV-VAR) model to explore the time-varying property of the link between Sino-US political relations and trade. The results indicate that the association of these two variables appears to be unstable. Sino-US political relations have positive and negative impacts on their bilateral trade, and the impact on Chinese imports is stronger than on its exports. In turn, Chinese imports from the US lead to political conflict, while Chinese exports promote peace. The interaction mechanism may originate from the expectations of the future trade environment caused by trade policy uncertainty. The interactions between Sino-US political relations and bilateral trade at different time points are also investigated. The results demonstrate that the link between these two variables is slightly different, depending on the specific status of the bilateral political relationship (friendly, neutral or hostile). Both China and the US should seek common interests to maintain a stable political relationship, and even with an increasing volume of bilateral trade, the risk of political conflicts should not be neglected.