Based on the density functional theory (DFT), using full-potential linearized augmented plane wave and improved local orbital (APW+lo) method, the structure and magnetism of the rare-earth permanent magnetic materials YFe11Ti are analyzed and calculated. The formation energy of YFe12，Y2Fe17 and YFe11Ti are calculated, The stabilization effect and the possible positions of the substituted atom Ti are discussed. The magnetic moments for the system and respective atoms are obtained. The calculated result is consistent with the experiment. The contributions of the density of states of the electrons to the magnetism are discussed.