The invention belongs to the field of radar signal processing, and discloses a low-altitude target tracking method based on multi-waveband two-grade information fusion. The method comprises steps of acquiring radar echo signals to obtain position information of an optimal observation target of the kth group of M-frame echo signal of the first waveband in a three-dimensional coordinate system; carrying out first grade observation fusion to obtain target position information of the kth group echo signals of the first waveband after the first grade observation fusion; inputting the target position information of the kth group echo signals of the first waveband, the filtering result of the k-1th group of echo signals of the first waveband and intervals of the observation fusion time into a filter to carry out tracking filtering and successively obtain filtering results of the K group of echo signals of each waveband in L wavebands; and setting filtering fusion time reference, and carrying out second grade observation fusion on target position information of the filtering results of K group of echo signals of each waveband in L wavebands on each filtering fusion time reference so as to obtain a target tracking result. Thus, detection probability and stable tracking performance of a sea-surface target can be improved.