The invention discloses a canagliflozin of crystal form B, and a crystallization preparation method thereof. The X-ray powder diffraction pattern of the canagliflozin of crystal form B has characteristic peaks at diffraction angles 2theta with the values of 3.4+ / -0.1, 6.6+ / -0.1, 12.6+ / -0.1, 13.2+ / -0.1, 15.3+ / -0.1, 15.6+ / -0.1, 16.5+ / -0.1, 19.4+ / -0.1, 19.8+ / -0.1 and 23.7+ / -0.1. The method has the advantages of high efficiency, easy operation and short time. Canagliflozin crystals of crystal form B prepared in the invention have a large solubility and a fast dissolving rate, the above product has a purity of above 99%, and has a yield of about 95%, and the purity, the color and the form of the product are unchanged after the product is stored under normal temperature dry conditions for 100d. The product has the advantages of easy crushing, easy addition of medicinal compositions, low cost, and easy commercial industrial large-scale enforcement.