Since the outbreak of the global financial crisis in 2008, the United States, Japan, Europe and other developed economies have fallen into the dilemma of weak economic growth, and their economic growth has always been significantly lower than the pre-crisis level. According to the secular stagnation theory, this is because the equilibrium real interest rate continues to decline and has fallen into the negative range. The central bank is constrained by the zero zero limit and it is difficult to lower the real interest rate to the equilibrium real interest rate. 
China's real interest rate has a wider range of adjustment and is therefore easier to fall to the equilibrium real rate
 the relatively high real interest rate leads to the continuous suppression of aggregate demand (especially investment demand). That is why, even with zero interest rates in the US, Japan and Europe, output gaps remain negative and recovery is hard to achieve. According to this theory, some argue that China's economy also faces a lack of investment demand and a prolonged period of stagnation.