Abstract: Under the framework of the extended endogenous economic growth model， this paper uses SV-TVP-FAVAR model to analyze the optimization and adjustment direction of fiscal expenditure structure in different stages of the economic cycle. The results show that during the recession caused by the economic crisis， the structural optimization direction of increasing the proportion of economic construction expenditure and health expenditure is more effective in promoting economic recovery. However， when the cause is the COVID-19 Pandemic， it is more effective to increase the proportion of health expenditure， cultural expenditure and educational expenditure. In the period of economic recovery， the structural optimization direction of increasing the proportion of cultural and educational expenditure and health expenditure is more effective in regulating economic growth. In the period of economic stability， the structural optimization direction of increasing the proportion of economic construction expenditure and cultural and educational expenditure is more effective in regulating economic growth.

Key words: fiscal expenditure structure; economic growth; SV-TVP-FAVAR model