<p>Thin-walled components possess high strength and lightweight characteristics; thus, they are widely used in aerospace, automotive, and other industrial fields. However, their low stiffness makes them susceptible to deformation induced by cutting forces during machining, which leads to poor form accuracy. To address this issue, this paper proposes an in-process deformation estimation and compensation method. Because direct, accurate measurement of the deformation at the cutting point is challenging, the deformation is estimated based on the deformations measured at points in the uncut area along the same axial line as the cutting point. To establish the deformation relationship along the axial line for estimation, finite element method simulations are conducted to generate axial deformation profiles corresponding to different cutting force locations. Additionally, a calibration coefficient obtained through experiments is applied to enhance the accuracy of the deformation estimation. Then, the estimated deformation is fed into the control loop of the fast tool servo system to compensate for machining-induced deformation effectively. To validate the effectiveness of the proposed method, machining experiments on sinusoidal pit arrays and sinusoidal grid microstructures are performed. The experimental results demonstrate that the proposed method substantially improves machining accuracy.</p>