The work aims to improve grinding efficiency of internal surfaces on titanium alloy spatial elbows. The method of magnetic abrasive finishing (MAF) was used to enable magnetic particles to rotate with polishing device and complete reciprocating motion along central axis of an elbow driven by a manipulator arm, and internal surface of the elbow were ground. Magnetic fluxing devices affecting magnetic abrasive grinding process were selected for analysis, and grinding tests were performed in the method of response surface method (RSM) provided with main process parameters (magnetic pole revolving speed, magnetic abrasive particle size, axial feed rate) affecting grinding, the optimum grinding parameters were obtained from the test data, and feasibility and reliability of optimized process parameters were verified. Finally, morphology of ground surface was analyzed with super-depth 3D electron microscope and roughness tester. Analysis of test data, best effects could be achieved by using magnetic fluxing devices at included angle of 60° provided with magnetic pole revolving speed of 550 r/min, magnetic abrasive particle size of 200 μm and axial feed speed of 1 mm/s. Surface roughness of the internal surface of spatial elbow decreased to 0.12 μm during 30 min processing, processing efficiency increased by 25% compared with 40 min required to reach the same state without the optimum conditions. In addition, gray rust, processing texture and scratches on the surface were fully removed, and surface quality became more uniform, fine and bright. Test analysis in response surface method and shape selection of magnetic fluxing device can effectively improve efficiency of processing internal surface of spatial elbow with polishing devices, and also save processing time.