The invention discloses an automatic positioning method for a 3D printing external fixing brace based on support minimization, and relates to the technical field of 3D printing, and the method comprises the following steps: S1, carrying out two-stage screening on triangular patches, and extracting real suspension points; s2, constructing a target function based on the real suspension point, and obtaining an optimal positioning posture according to an optimal solution of the target function; and S3, 3D printing is conducted according to the self-adaptive printing parameters and the optimal positioning posture. According to the method, the technological characteristics of three-axis printing are fully considered, the solution is reliable and feasible, and the method can be easily integrated into an existing
slicing software workflow.