The invention proposes a method for improving the resolution through time-varying frequency spectrum continuation, and the method comprises the following steps: dividing seismic data into different time windows; carrying out the continuous wavelet transformation of the seismic data in each time window; carrying out the frequency spectrum continuation of each piece of seismic data after wavelet transformation; and reconstructing seismic data through inverse wavelet transformation. Through a theoretical model and actual seismic data testing, the method improves the resolution remarkably through the time window dividing high-frequency continuation, and each time window achieves the optimal resolution. The method is well targeted. From the aspect of seismic data spectrum continuation simulation effect, the method has the advantage of remarkably improving the resolution, generates no false event while improving the resolution, and is high in credibility.