Sector capacity estimation plays an important role in applied research of airspace management.Previous researches manifest that sector capacity should be influenced by its standard flow,or routes in that sector.However,if air traffic controller(ATCO)workload busy levels(level of proactivity of an ATCO)are ignored,the estimated sector capacity may not be accurate.There is a need to compare the estimated sector capacity with and without busy levels consideration,both with differentiated routes consideration.This paper proposes a method for sector capacity estimation based on ATCO workload considering differentiated routes and busy levels.Firstly,the main routes in the sector are identified,and for each route,the ATCO workload per flight is determined.Secondly,the workload for each route at three busy levels is determined.Regression analysis is then applied to determine the relationship between workload and the number of flights(with and without considering busy levels)in 15 min and 1h time slices.Sector capacity is then determined on the basis of a specified workload threshold,for the two cases with and without considering busy levels.Comparing the two scenarios and following validation by ATCO survey,it is found that capacity estimation considering busy levels is a more realistic and accurate approach.The validated capacity values for the Zhengzhou approach(ZHCC AP)airspace sector accounting for the busy levels were determined accurately as 10 and 33 flights for the 15 min and 1h slices,respectively.The corresponding results without considering busy levels were 12 and 41 flights for the 15 min and 1h time slices,respectively. Sector capacity estimation plays an important role in applied research of airspace management. Previous researches manifest that sector capacity should be influenced by its standard flow, or routes in that sector. Host, if air traffic controller (ATCO) workload busy levels (level of proactivity of an ATCO) are ignored, the estimated sector capacity with not with busy levels consideration, both with differentiated routes consideration.This paper proposes a method for sector capacity estimation based on ATCO workload considering differentiated routes and busy levels. Firstly, the main routes in the sector are identified, and for each route, the ATCO workload per flight is determined. Secondly, the workload for each route at three busy levels is determined. Regression analysis is then applied to determine the relationship between workload and the number of flights with (with and without considered busy levels) in 15 min and 1h ti me slices.Sector capacity is then determined on the basis of a specified workload threshold, for the two cases with and without considering busy levels. Comparing the two scenarios and following validation by ATCO survey, it is found that capacity estimation estimates busy levels is a more realistic and accurate approach. The validated capacity values ​​for the Zhengzhou approach (ZHCC AP) airspace sector accounting for the busy levels were determined as 10 and for the 15 min and 1h slices, respectively. were 12 and 36 for 15 min and 1h time slices, respectively.