Most of the external tubes of aero-engines are titanium alloy bends. The inner surface defects caused by the bending process in the cold bending process are difficult to be removed by traditional grinding methods, which is a technical bottleneck. The grinding and polishing of the inner surface of the titanium alloy elbow can be achieved by the magnetic abrasive finishing. From the case of the application of the titanium alloy catheter inside the aero-engine, the basic principle of the inner surface of the magnetic grinding titanium alloy elbow is analyzed. At the same time, the key technical problems in the process of designing the grinding device is analyzed. Through theoretical anatomy and finite element simulation analysis of the magnetic field source and magnetic pole shape and trajectory design, a set of relatively complete process plans is obtained. Experimental results show that the magnetic abrasive machining method has good effect on the internal surface of the elbow defect removal.