The invention discloses a preparation method for an anatase titanium dioxide nanocrystalline mesoporous microsphere. A butyl titanate alcoholic solution is prepared from butyl titanate and alcohol; a gelatin solution is prepared by gelatin and acetic acid; the gelatin solution is slowly dropped into the butyl titanate alcoholic solution to obtain a sol solution; then the sol solution is aged and dried to obtain dry gel; the dry gel is put into distilled water for boiling; after filtration cleaning is executed, the product is cleaned through the alcohol and then is dried to obtain the anatase TiO2 nanocrystalline mesoporous microsphere. The preparation technology disclosed by the invention is simple and favorable for large-scale popularization and application, and a used solvent is safe and environment-friendly.