Geometric and electronic structures of three polymorphs of BiPO_4(m MBIP, n MBIP and HBIP) have been investigated by the first-principles calculations. The results show that PO_4 tetrahedron in n MBIP is distorted most, and m MBIP possesses minimum effective mass of carriers in three polymorphs of BiPO_4. Further, the leading role of inductive effect of dipole moment or effective mass of carries in the separation of electron-hole pairs is analyzed. Based on the fact that n MBIP has higher photocatalytic activity than m MBIP, it can be inferred that the inductive effect of dipole moment deriving from distorted PO_4 tetrahedron is the dominant factor affecting the separation efficiency of carries. The calculated results represent that n MBIP has more appropriate redox potential and narrower band gap than others. These findings may provide meaningful guidance for further understanding on the relationship between unique crystal structure and photocatalytic activity of BiPO_4. Geometric and electronic structures of three polymorphs of BiPO 4 (m MBIP, n MBIP and HBIP) have been investigated by the first-principles calculations. The results show that PO 4 tetrahedron in n MBIP is distorted most, and m MBIP possesses minimum effective mass of carriers in three polymorphs of BiPO 4. Further, the leading role of inductive effect of dipole moment or effective mass of carries in the separation of electron-hole pairs is analyzed. Based on the fact that n MBIP has higher photocatalytic activity than m MBIP, it can be inferred that the inductive effect of dipole moment deriving from distorted PO_4 tetrahedron is the dominant factor affecting the separation efficiency of carries. The calculated results represent that n MBIP has more appropriate redox potential and narrower band gap than others. for further understanding on the relationship between unique crystal structure and photocatalytic activity of BiPO_4.