The polycrystalline films LiNbO3 on the substrates (001) Si with the spontaneous orientation of grains are developed by the ion-beam sputtering method. The mechanisms of conductivity in the interval of temperatures T = 90-400 K are investigated by the method of the current-voltage characteristics. The initial site of the current-voltage characteristics is defined by the properties of contact Si-LiNbO3 and is described within the framework of Fowler-Nordheim tunneling and Richardson-Schottky emission. At the high voltage, the conductivity is defined by the volume of the film LiNbO3 and is described by the thermo-assisted tunneling of the electrons through the intercrystalline barriers with the height phi(b) = 0.7 eV. The parameters of the traps presented in the band gap of LiNbO3 are defined.