Wafer-scale flexible surface acoustic wave (SAW) devices based on AlN/silicon structure are demonstrated.The final fabricated devices with a 50μm-thickness silicon wafer exhibit good flexibility with a bending curvature radius of 8 mm.Measurements under free and bending conditions are carried out,showing that the central frequency shifts little as the curvature changes.SAW devices with central frequency about 191.9 MHz and Q-factor up to 600 are obtained.The flexible technology proposed is directly applied to the wafer silicon substrate in the last step,providing the potential of high performance flexible wafer-scale devices by direct integration with mature CMOS and MEMS technology.