Geometry calibration of microphone arrays is an essential preprocessing step for many applications, e.g., beamforming in deformable arrays. However, most existing geometry calibration methods involve the use of non-convex cost functions, suffering from the local minimum problem and low stability. To overcome these drawbacks, we introduce a novel approach that leverages the geometry feature of deformable linear arrays (DLAs) as an additional constraint. The proposed method employs Bézier curve fitting, utilizing the characteristics of Bézier curves to model the geometry feature. Specifically, we first introduce the general form of the geometry calibration problem, and an alternative approach is then proposed for a specific scenario where quadratic Bézier curves are used to fit the array shape. Finally, an additional scale modification is adopted to improve the performance of the proposed method in real scenarios. Simulations and real experiments validate the effectiveness of the proposed method for geometry calibration of DLAs.