This paper addresses the relationship among the complex indicators of area control sectors using covariance matrix and hierarchical clustering method. Seven complexity indicators are built considering the structural and flow distribution features of area control sectors. Thirty-seven area control sectors in China are chosen to clarify the correlations among complexity indicators using visualized covariance matrix. It is found that the area of each sector varies greatly (coefficient of variation 194.75%) while flow distribution of different routes in sample sectors has little change (coefficient of variation 9.02%). The larger the sector range is, the more uniform the flow distribution is on each path (correlation coefficient 0.54~0.59); the larger the sector range is, the lower the sector flow is (correlation coefficient -0.06~-0.13). Single linkage method is introduced to cluster these complexity indicators. Clustering tree shows that static complexity indicators and dynamic complexity indicators can be well distinguished setting the distance between classes 0.70. It is found that static complexity indicators share more commonness than dynamic ones.