Neo-Keynesian economics came into being in 1980s, and its policy proposition flourished in 1990s. Its representatives are mostly American economists, such as Q.A. akerlof, J.Yellen, G.Manji, B.Banach and others. Neo-Keynesian economics insists on government intervention in the economy, but it absorbs the rational expectation view of the rational expectation school and the view that "expected macroeconomic policies are invalid". They believe that in the contemporary market economy, information asymmetry and changes in wages and prices are sticky, so that there will still be deviations from the natural unemployment rate and insufficient effective demand in the short term. Therefore, demand management policy is still necessary and effective. Neo-Keynesianism not only insists on the short-term demand management of traditional Keynesianism, but also emphasizes the idea that the supply school regulates the economy from the supply side, and advocates considering economic policies from the long-term and supply side. Neo-Keynesianism also emphasizes the consolidation of fiscal policy, arguing that fiscal deficit is harmful to the economy, which will lead to a decrease in investment (basic effect) and an increase in trade deficit. In addition, neo-Keynesians have also studied some new phenomena and mechanisms. For example, in the mechanism of monetary policy, we should not only consider interest rates, but also consider the ubiquitous credit rationing mechanism. Compared with traditional Keynesianism, new Keynesianism has undergone some major changes. The macroeconomic policies they advocate are more comprehensive and in-depth, taking into account both demand and supply. Give consideration to both long-term and short-term; We should pay attention to both the short-term effects of fine-tuning policies and the long-term effects of structural policies. It can be said that neo-Keynesians inherited the basic proposition that traditional Keynesian countries should intervene in the economy, not only absorbed some reasonable theories and policy propositions of neoclassical economics, but also developed the theory of state intervention in the economy on the basis of absorbing some experiences and lessons from macroeconomic practice since the 1980s, which made the policy system of state intervention in the economy develop to a new level.