The nondestructive evaluation of stress using guided waves through the acoustoelastic effect has significant importance for the safety of the structure. In this paper, a Semi-Analytical Finite Element (SAFE) method is used to develop the acoustoelastic theory of guided waves propagating in plate-like structures with arbitrarily shaped cross-sections. Based on the anisotropy of the material induced by the axial force, a method for in-situ detection of biaxial stress through multi-angle dispersion change was developed. The inversion algorithm was validated by data of the SAFE method and the Sweeping Frequency Finite Element Modeling (SFFEM) method, respectively. The inversion results of S0 mode under this method are mainly studied, which can achieve accurate stress in-situ detection of the plate-like structure, and the Root Mean Square Error (RMS) can reach below 1%.