This paper first theoretically analyzes that Economic Policy Uncertainty （EPU） will inhibit trade from three sources: sunk costs, actual demands, and expectations. Then, based on the traditional gravity model, it introduces EPU to the model and uses country-pair quarterly data to empirically study the extent of the trade impact of EPU, and further discusses whether there are differences in the degree of influence of EPU on trade under different conditions. 　　The conclusions of this study are as follows: （1） The absolute value and growth of EPU both have an adverse impact on the trade scale, but the impact of exporter’s EPU index is insignificant; （2） EPU’s inhibitory effect on trade is related to macroeconomic status of importers, especially in countries with high unemployment; （3） There is a threshold effect of EPU on trade, and the marginal effect is significantly larger at a high level of EPU than at a low level of EPU.　　The conclusions of this paper provide important inspirations for the stable growth of global trade: under the current situation of relatively low growth of international trade, reducing the level of EPU is an important way to achieve stable growth of global trade and overcome existing difficulties. Besides, the international community should attach great importance to the detrimental effects of EPU on trade and adopt effective measures to reduce EPU. Specifically, countries should firmly oppose the " reverse globalization”, and strengthen the coordination of international economic policies and jointly safeguard multilateral cooperation mechanisms.　　The contributions of this paper are as follows: First, a relatively comprehensive mechanism of EPU’s impact on trade is proposed. This paper believes that as a broader measurement of policy uncertainty, EPU may not only affect the sunk costs of trade and entry and exit decisions, but also affect the scale of external demand facing traders and the expectations of traders. Second, through country-pair data, this paper empirically analyzes the trade inhibition effect of EPU, and points out that the impact of EPU has a non-linear characteristic, and the degree of its influence depends on both the macroeconomic status and the degree of EPU itself. Third, the conclusions of the study have strong policy implications. This study not only provides a new explanation for the low-speed growth of global trade in recent years from the perspective of EPU, but also provides more theoretical basis for countries to strengthen the policy cooperation and maintain the multilateral system.