To overcome the technical problems of low finishing efficiency and quality of the inner wall of deep holes， an auxiliary magnetic field block was added to the traditional needle-type magnetic compound fluid （MCF） polishing tool head. In addition， an MCF deep hole polishing tool and processing method based on the h-shaped polishing tool head are proposed. COMSOL Multiphysics was used to establish a combined model of permanent magnet magnetic field， and the head structure of the h-shaped polishing tool was designed with a uniform magnetic field. MCF deep hole polishing magnetic field model and flow field model were established， and magnetic-fluid coupling simulation was conducted to analyze the MCF fluid flow characteristics. Considering brass H62 as the sample material， experiments with different polishing process parameters were carried out. Further， the surface morphology， roughness， and material removal rate of the sample before and after polishing were compared， and the simulation model was verified. The experimental results suggest that the best polishing effect is obtained when the horizontal distance between the two magnets of the h-shaped polishing tool head is 8 mm， polishing speed is 1400 r/min， polishing gap is 1 mm， particle size of the alumina abrasive grain is 0.5 µm， surface roughness is 173 nm， and material removal rate is 0.84 mg/min； in addition， under these conditions， the polishing effect produced by the h-shaped polishing tool head is better than that produced by the needle polishing tool head. The MCF deep hole polishing method proposed herein can effectively improve the surface quality of the inner wall of the hole. In addition， the proposed method is effective and can lay the foundation for subsequent applications.