Based on the data from successive national forest resources inventories and annual monitoring of provincial forest resources in Zhejiang Province during 1979-2019,we analyzed the changes in the age group structure of arbor forests in Zhejiang Province over the past 40 years and predicted the development in the next 10 years by adopting methods such as statistical comparisons,analysis of the balance rate,and projections of area transfer.The results show that:1)During the 40 years,the changes in the age group structure of arbor forests in Zhejiang Province can be obviously divided into two phases.From 1979 to the end of the 20th century,there was a period of rapid growth in the area of arbor forests,and the age group equilibrium rate increased from 0.464 to 0.546,and the optimization of the age group structure was not the main successional feature;after entering the 21st century,the area of arbor forests was stagnant,and the age group equilibrium rate increased from 0.546 to 0.758,the optimization of age group structure has become the main successional feature;2)The age group structure of arbor forests in Zhejiang Province is now close to an ideal state,with the potential for forest resources to be fully cultivated,and it is predicted that it will reach an ideal state by 2029;3)At present,the arbor forests in Zhejiang Province have the problem of the overall age complementary effect of the stand,which means a relatively young age of one species and the relatively old age of another.It should be noted that the overall better age structure of the stand may mask the uneven age structure of individual species.Based on the current status of the age structure of arbor forests in Zhejiang Province and the target orientation of sustainable management,measures to optimize the age structure are proposed,with a view to promoting the improvement of the quality of forest resources and the capacity of carbon sequestration and sink enhancement.