The embodiment of the invention provides a method and a device for predicting cracks by earthquake longitudinal wave multidirectional attribute ellipse fitting. The method comprises the steps of performing center symmetry treatment on earthquake attribute data comprising at least threes direction according to the line measuring direction so as to generate the earthquake attribute data with complete directions; performing ellipse fitting on the generated earthquake attribute data with the complete directions; determining the ellipse oblateness as the growth strength of the crack. According to the embodiment of the invention, the central point of the ellipse is enabled to position at the original point of the polar coordinates, and the parameters needing inversion for the longitudinal wave crack prediction is reduced to 3 from 5, so the inference of noise to the crack feature inversion is reduced; meanwhile, the ellipse oblateness is determined as the crack growth strength which is more reasonable compared with the mode of describing the crack growth strength with the ratio between the long axis and the short axis in the prior art.