In order to improve the measurement accuracy of the three-dimensional shape of the flexible mechanism, a multi-core optical fiber three-dimensional shape reconstruction method based on curvature and angle correction was proposed. By introducing directional angle and curvature correction coefficients, the flexible three-dimensional deformation multi-core fiber reconstruction algorithm was improved; the multi-core fiber grating sensing array was fabricated by using excimer laser and phase mask method, and the multi-core fiber three-dimensional shape reconstruction experiment system was established; the shape reconstruction error under different curvature scale factors was measured in the experiment, and the shape reconstruction error before and after the curvature and angle correction was analyzed; Through the cubic spline interpolation of the strain and the correction of the direction angle and curvature, the average value of shape reconstruction error was 0.74 mm and the maximum value was 1.64 mm; By using the calibrated multi-core optical fiber sensing system to carry out the three-dimensional helix deformation reconstruction experiment, the reconstruction accuracy was improved by 10.2%. The research results show that the multi-core optical fiber 3D shape reconstruction method based on curvature and angle correction has higher accuracy, showing important application prospects and values in real-time monitoring of the 3D shape of flexible mechanisms.