Sealing technology is critical to ensure the efficiency, reliability and durability of a high-performance aircraft engine. This study proposes a coupling design method for the sealing system that incorporates a labyrinth seal as an element of the turbofan engine system. The method considers not only the operating parameters of the working fluid but also the relationship between the sealing system and adjacent subsystems, such as the buffer, pre-oil, oil and unload chamber, as well as the calculation of axial force, resulting in a qualitative transition of the design from the individual seal to the sealing system and overall engine performance. Numerical simulations of pressure, temperature, and heat distribution within chambers of the secondary air system are conducted using a high-precision computational fluid dynamics (CFD) model in conjunction with finite element analysis (FEA). The study examines the effects of various labyrinth seal positions on the chamber and the axial force. The results indicate that the labyrinth seal located near the oil chamber has radial clearance restrictions imposed by the maximum oil temperature, and that seal position of the unload chamber significantly influences the axial force. And simulations elucidate the thermal and fluid dynamic interactions within the chambers, emphasizing the importance of striking a balance between clearance design and thermal management.