ZnMn2O4 flower-like microspheres self-assembled by curved nanoplates are synthesized by calcining the ZnMn2-ptcda MOF precursors. These curved nanoplates consist of small particles with controlled particle size. The band gap of the ZnMn2O4 microspheres is increased to about 2.1-2.6 eV. The enlarged specific surface areas, porosity and decreased particle size are also investigated in details. Owing to the self-assemble mesoporous nanostructure, the photocatalytic performance on reduction of CO2 into CO is enhanced significantly for ZnMn2O4 flower-like microspheres, compared with ZnMn2O4 nanoparticles. This suggests that ZnMn2O4 flower-like microsphere can be regarded as a promising photocatalyst for photo-reduction, photo-degradation and photosynthesis.