The invention discloses a heterogenous junction film material with the white light photovoltaic effect and a preparation method thereof, which belong to the technical field of an optical sensor and photoconducting device materials. The method of the invention comprises the steps of depositing an aluminum oxide layer, a cobalt layer and an iron doping carbon layer on an n-Si (100) substrate under the condition of the vacuum between 10 to 4 Pa magnitudes at the deposition temperature between 300 DEG C and 500 DEG C to obtain the Fe-C/Co/Al2O3/Si heterogenous junction film material, wherein the iron doping carbon layer is used as an active layer with the thickness between 20 and 100 nm; and the aluminum oxide layer is an insulation layer with the thickness between 2 and 3 nm, and the cobalt layer is a transition layer with the thickness between 5 and 10 nm. The obtained product has the response to visible light under the white light or visible light wave band at the room temperature, hasobvious photovoltaic effect, and can generate open circuit voltage between 0.15 and 0.30 V or short circuit current with the current density between 2 and 4 mA/cm<2> under the irradiation of the white light of 100 mW/cm<2>.