As seismic signals propagate underground, the subsurface media absorb high–frequency components, decreasing seismic resolution and limiting the identification and characterization of thin reservoirs. To address the limitation, this paper proposes a multichannel spectral fitting (MSF) method. The MSF method aims to enhance seismic resolution by considering the spectral characteristics and the correlations between adjacent seismic traces. The key to the MSF method involves utilizing the amplitude spectrum of the attenuated Ricker wavelet to construct an objective function for spectral fitting, leading to improved seismic resolution. Furthermore, the MSF method establishes the correlation between adjacent seismic traces as a constraint to stably solve the target parameters based on the entire seismic spectrum, which helps obtain horizontally consistent and more realistic seismic signals. Synthetic and field seismic examples demonstrate that the proposed method not only provides higher-resolution seismic signals but also reveals more fine details of thin reservoirs compared to the time-variant spectral whitening method. It is concluded that the MSF method is a promising tool for seismic signal processing.