Micron-scale superalloy honeycomb cores （MSSHCs） have the advantages such as light weight，high temperature resistance，and excellent sealing，and have been used as the core material of key components in new generation aero-engines and hypersonic aircrafts.An MSSHC is extremely small，with an area of only 1/10 of a common superalloy honeycomb core.Therefore，it has the difficult machining characteristics of superalloy and thin-wall structure at the same time.This makes MSSHCs extremely prone to the defects such as burrs，core deformation，and tearing during machining.To solve the above problems，the ultrasonic assisted machining technology for MSSHCs is designed.The cutting angles of single and double walls of MSSHCs are investigated according to the geometric relationship between the workpiece and tool during side machining.Based on the grinding/milling experiment，the mechanisms of ultrasonic grinding/milling of MSSHCs and defect formation are revealed.The results show that the cutting angles of single and double honeycomb walls are 60° and 0°，respectively.Under the same machining conditions，compared with the grinding wheel，the designed milling cutter has smaller cutting force and shorter burr length.Ultrasonic vibration is beneficial to crack propagation，reducing the grinding force，burr length，core deformation，and tearing defects.The above investigations provide a theoretical basis for the high efficiency and low damage machining of MSSHCs.