The invention provides a novel catalase model complex [MnLBr]2, and a biosensor produced from the catalase model complex. A preparation method of the [MnLBr]2 comprises the following steps: adding an L-containing methanol solution to a methanol solution containing metal ions in a dropwise manner under the protection of nitrogen while stirring; and stirring the solutions for 1d, carrying out rotary evaporation to remove a part of a solvent, adding a proper amount of Et2O to obtain a precipitate, and carrying out suction filtration. The preparation method is simple and is convenient to promote, and a catalase model ligand and the complex have high activity.