The invention discloses a lithium titanate negative electrode material and a preparation method therefor. Metatitanic acid is adopted to absorb lithium from brine through ion exchange; then a lithium salt is added; the molar ratio of lithium to titanium is adjusted to be 4 to 5; and the lithium titanate negative electrode material is obtained by sintering through a solid-phase method. The lithium titanate negative electrode material and the preparation method therefor have the following technological advantages that: 1) the natural lithium-bearing brine is taken as the lithium source comprehensively, so that the usage amount of the refined lithium salt is lowered, and the material synthesis cost is greatly lowered; 2) due to the ion exchange method, the lithium source and the titanium source are uniformly distributed on the atomic level; the rearrangement of lattice matrix can be realized through short-range diffusion easily, so that the synthesis process is low in cost, and relatively low synthesis temperature and relatively short synthesis time can be realized; 3) due to the low synthesis temperature, the grain fineness distribution is uniform, and an more excellent electrochemical performance is presented after the carbon layer is coated in an in-situ manner; and 4) a higher advantage is realized compared with other schemes in the aspects of economic efficiency and environmental protection, and particularly, the practical meaning of extracting lithium from liquid lithium resource to synthesize the battery material is achieved.