The development of ‘Digital/Analog-Hybrid WINd tunnel (DAHWIN),’ which is an innovative system integrating CFD (Computational Fluid Dynamics) with EFD (Experimental Fluid Dynamics), is presented. The aim of DAHWIN is to improve efficiency, accuracy, and reliability of aerodynamic characteristics evaluation in aerospace vehicle developments through mutual support between EFD and CFD. DAHWIN is constructed as a system seamlessly connecting two large facilities, JAXA 2m x 2m Transonic Wind Tunnel for EFD and JAXA Supercomputer System for CFD. The function of this system consists of optimization of test planning, an accurate correction of the wind tunnel wall and support interaction effects, quasi-simultaneous monitoring of EFD data in comparison with corresponding CFD data, the most probable aerodynamic characteristics estimation based on both EFD and CFD data, and so forth. Each function is described with some examples of applications. Key technical challenges in the system development, such as an automatic grid generator, high-speed CFD solver, and a high-speed data processing technique for image measurement data, are also addressed. Some preliminary applications of DAHWIN to practical wind tunnel tests, such as civil transport tests, showed the usefulness and reliability of DAHWIN in terms of increasing efficiency and accuracy of both EFD and CFD.