In the semiconductor lithography process, blank masks are primitive optical flats, and nanometer precision surface profiles play an important role in improving the performance of advanced chips. To measure the surface profile and thickness variation of a blank mask, a method is proposed based on parameter time-domain estimation for wavelength phase-shifting interferometry of a blank mask. First, to ensure the validity of the measurements, the coupling relationship between the front and rear surfaces of the blank mask and thickness variation is determined according to the optical path tracing method, and the self-assessment rule for the error in wavelength phase-shifting interferometry is analyzed. Next, to avoid the influence of spectral distortion and cavity length on accuracy, the parameter time-domain estimation method is used to determine the carrier parameters. Concurrently, the initial phase is demodulated based on the weighted least-squares principle to reduce the sensitivity of the algorithm to anisotropic noise. Finally, simulations are conducted to analyze the influence of different factors on the measurements. In addition, comparison experiments are carried out at different cavity lengths, with 10^-3λ₀ as the magnitude of the blank mask interferometry error self-assessment index. The results show the effectiveness and stability of the proposed algorithm in measuring surface profiles and thickness variations of the blank mask, thereby providing a technical approach for advanced chip manufacturing.