As one of the important transition metal oxides, Co3O4 possesses an excellent property, which leads to the fact that Co3O4 is widely used in optical, electrical, magnetic, thermal and other fields. The crystals of Co3O4 can be used as heterogeneous catalytic materials and thereby have an irreplaceable position in many reactions. With the continuous study of the catalytic mechanism, it is found that the catalytic reaction process is not only affected by the particle size of the crystal catalyst, but also is sensitive to the crystal facet. Therefore, the study on crystal facet effect of transition metal oxides is of great significance for the in-depth understanding of heterogeneous catalytic reactions and the effective design of high-active catalysts. Co3O4 crystal has spinel structure with a mixed valence state of octahedral coordinated Co3+ and tetrahedral coordinated Co2+, and it shows the obvious crystal facet effect in different catalytic reactions. In this paper, the crystal facet effects of Co3O4 as heterogeneous crystal catalyst in thermal catalysis, photocatalysis, electrocatalysis and peroxidase-like catalysis in recent years are systematically reviewed. In combination with theoretical calculations, the reasons of these crystal facet effects are explained from the atomic structure of different crystal facets of Co3O4. Finally, the general law of crystal facet effect of Co3O4 in the above reactions is summarized, the shortcomings in current study on Co3O4 crystal facet effect are discussed, and the future development trend is reasonably prospected.