The present invention pertains to the technical field of pharmaceuticals, and specifically discloses a crystal form of a deuterated AZD9291, a method for preparing the crystal form, and a use of the crystal form. An X-ray powder diffraction of the crystal form of the deuterated AZD9291 measured using Cu-Kα rays has diffraction peaks at 7.1 ± 0.2, 8.5 ± 0.2, 9.4 ± 0.2, 10.3 ± 0.2, 15.1 ± 0.2, 16.3 ± 0.2, 18.7 ± 0.2, 22.0 ± 0.2, 25.6 ± 0.2, and 26.0 ± 0.2. The present invention further discloses a use of the crystal form of the deuterated AZD9291 in the preparation of medicaments for the treatment of cancer. The crystal form of the deuterated AZD9291 provided by the present invention has stable physical and chemical properties and good metabolic stability, and blood concentrations in vivo and concentrations in the brain thereof are significantly improved, achieving an improved therapeutic effect.
