This paper examines the effects and mechanism paths of monetary policy on firms' "short-term debt for long-term investment (SDFLI)" behavior using panel data of Chinese A-share listed firms from 2007-2019. The findings indicate that loose monetary policy suppresses corporate SDFLI behavior by lengthening corporate credit maturity structure through the credit maturity structure channel. In addition, heterogeneity analysis shows that loose monetary policy significantly inhibits the SDFLI behavior of state-owned enterprises(SOEs), non-high-tech firms, and firms in regions with high bank competition levels through the credit term structure channel, and the monetary policy credit term structure channel fails for non-state-owned enterprises(non-SOEs), high-tech firms, and firms in regions with low bank competition levels. The results of the heterogeneity analysis validate the plausibility that monetary policy affects firms' SDFLI behavior through the credit term structure channel.