In　mesoscopic　perovskite　solar　cells,　the　electron　transport　layer　plays　an　important　role　in　charge　extraction　and　determines　the　charge-transport　property　to　attain　a　superior　photovoltaic　performance.　Herein,　we　report　a　low-cost,　solution-based　deposition　procedure　of　decorating　graphene　quantum　dots　on　the　surface　of　mesoporous　TiO2　film,　expecting　that　a　more　effective　electron-transport　channel　can　be　formed　for　the　enhancement　of　solar　cell　performance,　finally,　an　impressive　power　conversion　efficiency　of　20.45%　is　achieved　in　the　resulting　optimized　perovskite　solar　cell.　Furthermore,　the　results　of　various　spectroscopic　characterizations　including　electronic　impedance　spectroscopy,　steady-state　and　time-resolved　photoluminescence　spectrum　elucidate　that　the　introduction　of　GQDs　on　the　surface　of　mesoporous　TiO2　film　not　only　enhance　the　electron　extraction　but　also　facilitate　the　charge　transportation　at　interface　between　the　perovskite　and　electron　transport　layer.