Abstract: The trade war triggered by the United States has brought great uncertainty to the trading environment on Chinese enterprises. Based on the text mining method and difference in difference(DID) model, this paper distinguished the enterprises' perception of uncertainty and investigated the impact on enterprises' R&D investment by Sino-US trade war. The empirical results show that: firms affected by Sino-US trade frictions significantly increase R&D investment, and the robustness tests show that this promoting effect is robust. Further research shows that the impact of Sino-US trade friction on R&D investment has strong heterogeneity: the promotion effect is more obvious in state-owned enterprises and low financing constraints enterprises.