Wavelength crosstalk problem occurs when there are too much multiplexing in fiber Bragg gratings or the limited bandwidth, and the performance of signal demodulation method is related to the accuracy of result. In this paper, a novel central wavelength demodulation method based on meta-heuristic algorithm is proposed, the least-squares function of the discrepancy between the actual spectrum and the theoretical spectrum is employed as the optimization objective, the marine predators algorithm with excellent exploitation and exploration capabilities is developed to solve the problem. Numerical simulation and experiment verify that the proposed algorithm is an effective and feasible wavelength demodulation method, which can realize the recognition of multi-spectral overlap and ensure the demodulation accuracy.