Hole-conductor-free carbon-based perovskite solar cells (C-PSCs) are known for their low-cost and superstability. In this work, different mesoporous structures, namely, mesoporous TiO2 + Al2O3 (mp-TiO2 + Al2O3), mpTiO(2) + ZrO2, mp-Al2O3, mp-TiO2, and blocking compact layer of TiO2 (bl-TiO2), were investigated and systematically compared. Results revealed that the performance of PSCs with double-layer mesoporous structure was better than that of the other mesoporous structures, especially PSC with the structure of mp-TiO2 + Al2O3 obtained the open-circuit voltage (V-oc) of 0.97 V and the current density (J(sc)) of 23.77 mA cm(-2), respectively, the photoelectric conversion efficiency (PCE) reached 11.3% because of the function of the mesoporous layer in separating TiO2 and carbon, thereby avoiding direct contact and reducing the leakage of the current. Al2O3 and ZrO2 are insulating materials that could effectively prevent electrons from transmitting back to C. The mesoporous structure of the device based on mp-TiO2 + Al2O3 was evenly distributed, the perovskite crystal particles based on mp-TiO2 + Al2O3 were enlarged, uniform, and relatively tight, and the grain boundaries between the perovskite crystal particles were remarkably reduced. Among the films, the perovskite film of mp-TiO2 + Al2O3 structure had the highest absorption intensity. This study provided a new basis for commercializing low-cost PSCs.