Movement of the renminbi (RMB) exchange rate is not only affected by economic factors, but also by political factors home and aboard. This paper analyzes the transmission mechanism of political cycles on the RMB exchange rate first, and then sets up a “political cycle spillover effect model” followed by an empirical analysis. We find that: (1) the US political cycle has a direct effect on the RMB exchange rate in the short run, which is mainly transmitted by capital flows and China’s exchange rate policy control; (2) the RMB exchange rate changes periodically in accordance with the US presidential election and midterm election cycle, with the appreciation ratio significantly lower in the first year of the election cycle, while significantly higher in the year after the midterm election; (3) The effect of the political cycle will not be affected by which party holds power, though it will be affected if the president and parliament are ruled by the same party. This paper not only extends the research of the influencing factors of the RMB exchange rate to the political field, but also sets up a use theoretical model to analyze the impact of political issues on the RMB exchange rate, providing a new perspective to fully understand the external environment of RMB exchange rate reform.