The invention discloses an earthquake stratum thickness variation analysis method in which a high-resolution instantaneous frequency decomposed on the basis of an empirical mode is used to analyze stratum thickness variation. Firstly, an earthquake signal is subjected to an empirical mode decomposing process to obtain a multilevel intrinsic mode function; then, the instantaneous frequency of the intrinsic mode function is calculated; and according to the variation of the instantaneous frequency, the stratum thickness variation is analyzed. According to the earthquake stratum thickness variation analysis method, a triple B spline is adopted as an interpolating function in the empirical mode decomposing process; the instantaneous frequency is calculated by using an instantaneous frequency calculation method with a damping factor on the basis of continuous wavelet transform; the obtained intrinsic mode function and instantaneous frequency profile have good lateral continuity and few false appearances, accord with the reality and also have good noise immunity. The earthquake stratum thickness variation analysis method is favorable for improvement of the reliability and the effectiveness of the earthquake stratum thickness variation analysis, is suitable for processing and explaining practical earthquake data, provides a powerful basis for predicting a reservoir stratum, and improves the precision of oil-gas field exploration and development.