Microbial carbon capture cell (MCC) was assembled with a photo biocathode where growing Scenedesmus obliquus to produce oxygen as an electron acceptor after the operation of photo-microbe fuel cell (PMFC) and an added CO2 photo-MFC (AC-PMFC). The voltage generation, dissolved oxygen and pH were measured over each day in the different systems. It was demonstrated that cell voltage produced by MFC was in line with the oxygen concentration in all systems with algae cathode. The pH of the electrolyte can also affect voltage generation. The highest voltage and power density of MCC were obtained in the three types of MFC with 492 mV and 102.3 mW/m2, respectively. Its maximum power density was higher than that of PMFC and AC-PMFC. The three systems received different concentrations of carbon dioxide for photosynthesis. The AC-PMFC achieved the lowest voltage and power density due to the excessive concentration of CO2, which could inhibit the biological activity and photosynthesis of microalgae. The scanning electron microscope (SEM) was measured to observe the morphology characteristics of algae on the cathode surface of MCC after long-term operation. A layer of in situ oxygen film with high concentration could be generated on the surface of algae biofilm and electrode plate. The electrochemical analysed demonstrated that the biofilm could not directly receive the electrons from the plate and had no biocatalytic activity. This biofilm could increase the rate of oxygen reduction, which can effectively reduce the resistance of the battery surface. Polymerase chain reaction (PCR) and 16S rRNA gene detection technology indicated that the Chao1 index in MFC was 170, while the PMFC was 152 and the MCC was 145. The oversaturated oxygen in the cathode could be transported to the anode by pipeline and affect the microbial community in the anode. This study could provide a basis for further understanding of algae-based microbial carbon-trapping cells to improve MCC performance.