Blade flutter is one of the most challenging problem in turbomachinery. The onset of blade flutter is usually characterized by aerodynamic coupling of adjacent blades in a blade-row due to the interaction of fluid and structure. The mechanism of blade vibration coupling via aerodynamic force is investigated with a fluid-structure interaction approach. The compressible unsteady Navier-Stokes equation coupled with the structure dynamic equations are solved for the blade vibration problem of a typical highly loaded compressor cascade. The calculated the aerodynamic damping is compared with experiment data. The time response of each vibrating blade is analyzed, and the aerodynamic damping characteristic and energy transfer between blades and its surrounding fluids are computed. Finally, the mechanism of coupling of blade vibration is identified.