Disclosed are a triazolesulcotrione crystal form C, a preparation method therefor, and a use thereof. The triazolesulcotrione crystal form C has an X-ray powder diffraction spectrum with characteristic peaks at a diffraction angle of 2θ of 6.8, 7.6, 9.4, 11.1, 13.1, 13.5, 14.6, 15.5, 16.1, 16.9, 18.0, 19.3, 19.4, 20.9, 21.9, 23.3, 23.6, 23.8, 24.8, 25.5, 26.1, 26.8, 27.8, 28.9, 30.1, 31.3, 33.2, 34.3, and 36.0 degrees, a 2θ error range falling within ± 0.2°. Upon testing, the triazolesulcotrione crystal form C has good stability: stored at a high temperature of 70°C for two months, the crystal form did not transform, the purity thereof was substantially unchanged, and the solubility thereof in water nearly doubled. Moreover, the crystal form C or a compound composition of the crystal form C with other active ingredients has good control effect on gramineous weeds and some broadleaf weeds in rice paddy, significantly superior to those of a crystal form A.
