Abstract: CuInSe₂ thin films were prepared by selenization of electrodeposited Cu-In precursors on Ti substrate under constant current with a carbon rod worked as anode. The phase composition and its influencing factors of Cu-In precursor films and CuInSe₂ thin films were studied. The results show that controlling deposition parameters can change the phase composition of Cu-In precursor films. When the atomic ratio of Cu/In is less than 1, the precursors containing the Culn phase and the Cu₂In phase are obtained at a lower concentration of InCl₃, a lower concentration ratio of H₃Cit to CuCl₂ and a higher current density. Stoichiometric CuInSe₂ films with a single chalcopyrite phase are synthesized from Cu-In precursors containing the Culn phase and the Cu₂In phase. The CuSe phase occurs in addition to the CuInSe₂ chalcopyrite phase in Cu-rich CuInSe₂ films synthesized from Cu-In precursors with only the Culn phase. Cu-In precursors with both the Culn and Cu₂In phases are favorable for CuInSe₂ films.