Provided are a crystal form B of a compound having the structure as represented by formula I, and preparation method and use thereof. The X-ray powder diffraction (XRPD) chart of the crystal form B has characteristic peaks at the following diffraction angles: 2.9±0.2°, 6.5±0.2°, 12.6±0.2°, 13.1±0.2° and 20.6±0.2°.