【摘要】By using the VAR model,we find that there exists no obvious Granger causality between investment and real GDP in China's economy.We also find that there is instantaneous causality between them.The Granger causality has the asymmetry in the business cycle.During the period of fluctuations,investment does Granger cause the real output in the aggregate level.During the period of recession,they do Granger cause each other in their stochastic components.