A method for extracting a downgoing wavelet and attenuation parameters from VSP data, wherein the method is a computer-implemented method, and the method comprises: picking up a P-wave first arrival from VSP data to obtain P-wave first arrival time, wherein the VSP data is obtained from seismic waves that are excited or received in a well; performing upgoing and downgoing P-waves separation processing on the VSP data to obtain downgoing P-wave data; performing a FFT on seismic data with.a preset time window length starting from the P-wave first arrival time and cut from the downgoing P-wave data to obtain FFT transformed downgoing P-wave data, and obtaining a multi-trace downgoing P-wave log spectrum based on the FFT transformed downgoing P-wave data; subtracting a downgoing wavelet log spectrum from the multi-trace downgoing P-wave log spectrum, to obtain a wavelet-corrected multi-trace downgoing P-wave log spectrum satisfying a preset requirement, the preset requirement being that a difference between parameters obtained from the multi-trace downgoing P-wave log spectrum and parameters obtained from the wavelet-corrected multi-trace downgoing P-wave log spectrum is within a preset range, the parameters including intercept and slope, performing, based on the parameters obtained from the wavelet-corrected multi-trace downgoing P-wave log spectrum, a correction and an inverse FFT on the FFT transformed downgoing P-wave data to obtain a downgoing wavelet; and obtaining attenuation parameters based on the P-wave first arrival time and the parameters obtained from the wavelet-corrected multi-trace downgoing P-wave log spectrum, the attenuation parameters including true amplitude recovery factor and Q factor; and characterized by the fact that subtracting the downgoing wavelet log spectrum from the multi-trace downgoing P-wave log spectrum to obtain the wavelet-corrected multi-trace downgoing P-wave log spectrum, comprises: performing flattening processing on each current trace of the multi-trace downgoing P-wave log spectrum; stacking the flattened multi-trace downgoing P-wave log spectrum to obtain a downgoing wavelet log spectrum; subtracting the downgoing wavelet log spectrum from each current trace of downgoing P-wave log spectrum, to obtain an updated trace of downgoing P-wave log spectrum; and replacing the current trace of downgoing P-wave log spectrum with the updated trace of downgoing P-wave log spectrum if a difference between parameters of the updated trace of downgoing P-wave log spectrum and parameters of the current trace of downgoing P-wave log spectrum is not within a preset range; iteratively performing the above steps until the difference between the parameters of the updated trace of downgoing P-wave log spectrum and the parameters of the current trace of downgoing P-wave log spectrum is within the preset range; and determining a final multi-trace downgoing P-wave log spectrum as the wavelet-corrected multi-trace downgoing P-wave log spectrum. picking up a P-wave first arrival from VSP data to obtain P-wave first arrival time, wherein the VSP data is obtained from seismic waves that are excited or received in a well; performing upgoing and downgoing P-waves separation processing on the VSP data to obtain downgoing P-wave data; performing a FFT on seismic data with.a preset time window length starting from the P-wave first arrival time and cut from the downgoing P-wave data to obtain FFT transformed downgoing P-wave data, and obtaining a multi-trace downgoing P-wave log spectrum based on the FFT transformed downgoing P-wave data; subtracting a downgoing wavelet log spectrum from the multi-trace downgoing P-wave log spectrum, to obtain a wavelet-corrected multi-trace downgoing P-wave log spectrum satisfying a preset requirement, the preset requirement being that a difference between parameters obtained from the multi-trace downgoing P-wave log spectrum and parameters obtained from the wavelet-corrected multi-trace downgoing P-wave log spectrum is within a preset range, the parameters including intercept and slope, performing, based on the parameters obtained from the wavelet-corrected multi-trace downgoing P-wave log spectrum, a correction and an inverse FFT on the FFT transformed downgoing P-wave data to obtain a downgoing wavelet; and obtaining attenuation parameters based on the P-wave first arrival time and the parameters obtained from the wavelet-corrected multi-trace downgoing P-wave log spectrum, the attenuation parameters including true amplitude recovery factor and Q factor; and performing flattening processing on each current trace of the multi-trace downgoing P-wave log spectrum; stacking the flattened multi-trace downgoing P-wave log spectrum to obtain a downgoing wavelet log spectrum; subtracting the downgoing wavelet log spectrum from each current trace of downgoing P-wave log spectrum, to obtain an updated trace of downgoing P-wave log spectrum; and replacing the current trace of downgoing P-wave log spectrum with the updated trace of downgoing P-wave log spectrum if a difference between parameters of the updated trace of downgoing P-wave log spectrum and parameters of the current trace of downgoing P-wave log spectrum is not within a preset range; iteratively performing the above steps until the difference between the parameters of the updated trace of downgoing P-wave log spectrum and the parameters of the current trace of downgoing P-wave log spectrum is within the preset range; and determining a final multi-trace downgoing P-wave log spectrum as the wavelet-corrected multi-trace downgoing P-wave log spectrum.