An improvement on photoconductivity of fullerene C-60 film has been observed after modification of laser irradiation at room temperature or at about 100 degreesC because some dimer, trimer and polymer of C-60 have been formed under the laser irradiation. This leads to some change of charge transfer (CT) states and reduction on resistance to transport of photocarriers. Another important reason for the great increase on photoconductivity of C-60 modified by laser irradiation at about 100degreesC (373 K) is thermal effect. Thermal treatment of the laser modified C-60 thin film at above 100 degreesC (373 K) for a few hours makes a great improvement on its photoconductivity because this treatment reduces trap centers for photocarriers resulted from an increase on its crystallinity and some change on its morphology. Oxygen has a great effect on photoconductivity reduction of the laser modified C-60 thin film. (C) 2003 Kluwer Academic Publishers.