The invention discloses a calcium titanate photonic crystal which has a three-dimensional ordered macroporous structure and is constructed by porous nano-sheets. A synthesis method of the calcium titanate photonic crystal comprises the steps of: firstly synthesizing polystyrene nano-spheres of uniform size by adopting a surfactant-free emulsion polymerization method, performing solvent volatilization assembly to form a colloidal crystal template, then filling calcium titanate precursors into the colloidal crystal template by utilizing a sol-gel method, and then performing calcination to obtainthe catalyst which has a three-dimensional ordered macroporous calcium titanate photonic crystal structure and is constructed by macroporous nano-sheets. The product obtained by using the synthesis method has a complete three-dimensional ordered macroporous structure, and a structural unit is a calcium titanate nano-sheet of a micropore mesoporous structure, so that advantages of a three-dimensional ordered macroporous structure, a grade pore structure and a two-dimensional nano-sheet layer structure are integrated, and the product has excellent photocatalytic performance; in addition, the calcium titanate photonic crystal has simple synthesis conditions, low cost and high repeatability, a prepared sample has complete morphology, and the calcium titanate photonic crystal is suitable for popularization and application.