Due to the wide wavelength coverage and dense transmission peak sequence of its spectrum, the Fabry-Perot etalon (FPE) for wavelength calibration of astronomical high-resolution spectra is expected to achieve higher calibration accuracy than traditional calibration sources. However, the unknown wavelengths of FPE transmission peaks pose a challenge for calibration. In this study, without precision measurement devices (such as Fourier transform spectrometers), the thorium-argon (ThAr) lamp, a conventional calibration source equipped on astronomical high-resolution spectrometers, was used to provide the FPE with wavelengths. Then, the errors in the ThAr wavelengths were corrected by using the dense transmission peak sequence of the FPE and the smooth relationship between the penetration depth of the dielectric reflective coating and the wavelength. Accurate wavelengths of the FPE transmission peaks were thus obtained, and wavelength calibration was performed. The calibration test on the fiber-fed high-resolution spectrometer of the Xinglong 2.16-m telescope showed that the wavelength calibration accuracy of the FPE reached 0.053 pm, which was significantly higher than that (0.290 pm) in the case of the ThAr being used alone.