For measurement methods of heterogeneous deformation strain with digital image correlation (DIC) technology, the accuracy of the reconstructed strain is greatly affected by the manually selected parameters. Through error analysis of the partial least squares (PLS) method and the regularized polynomial smoothing (RPS) method, a DIC-based self-adaptive strain field calculation method is proposed in this paper to solve this problem. The method searches for the parameter combination with the minimum total error within the given parameter range and uses the optimal parameters to obtain a strain field with higher accuracy. The measurement result is slightly affected by the type of the deformation field. The simulation experiment results show that the calculation accuracy of the method is close to that of the PLS method at the optimal parameters. This research effectively solves the problem of selecting the optimal parameters of PLS and RPS methods.