The utility model relates to a method for surveying oil and gas based on a Morlet spectrum, which comprises the steps as follows: firstly, Fourier analysis is implemented on seismic signals in a target reservoir of a seismic recording channel to obtain the frequency spectrum scope of the seismic signals; secondly, the seismic signals are analyzed by using continuous wavelet transform to obtain wavelet transform coefficient Wx (b, s); thirdly, the instantaneous amplitudes under different scale factors s are defined as follows: the instantaneous amplitude values [Ai(b0,1/ai)i is equal to 0, 1,..., N] corresponding with different scale factors ai is obtained for each time point b0; Lagrange splines are used for implementing interpolation; the amplitude values of any frequence at a b point can be obtained through the substituting of the corresponding a value; in the way, a connecting line of the discrete points forms the frequency spectrum of the b point, namely the Morlet spectrum; and fourthly, the absorption coefficients of each point are obtained according to the instantaneous amplitudes at any time point obtained in step 3); if the absorption coefficient Xi I of the point is lower than the absorption coefficient of a wall rock by more than ten percent, then the position is represented to comprise an air layer.