[en] To solve the difficulty of extracting orthogonal component of tidal harmonic from gravity earth tide signals, an orthogonal decomposition model for gravity earth tide signal is proposed in this paper. The harmonic component of the gravity earth tide signal is implemented orthogonal decomposition by the model in space, in order to realize the extraction of the harmonic component frequency reflects the independent geophysical information on the space. Thus, a new feature extraction method of gravity earth tide signal is presented by combining independent component analysis and differential evolution algorithm. It can be more effective to get the independent component which is consistent with the gravity solid tidal signal decomposition model. In the experiment, the measured signal is processed and compared with the theoretical value in Kunming area. Experimental result shows that the method can reveal the relationship of tidal harmonic component in gravity earth tide signals and this relationship corresponding to the gravity earth tide signal orthogonal decomposition model. Each spectral information component contained accords with theory value. (paper)