Abstract:  Recently, increasing attention has been paid to the catalytic oxidation of many organic contaminants. However, the use of oxygen or hydrogen peroxide as the oxidant has low efficiency because of the difficulty of O-O bond activation. Major O-O bond activation mechanisms by oxydases and oxygenases were reviewed in order to gain insights to increase the efficiency of Fe and Cu based biocatalyst for molecular oxygen and hydrogen peroxide utilization in environmental remediation. Multicoppor oxidases (MCOs) e.g., laccase (Lc) use a cluster of three copper atoms and one distant copper as the active center. MCOs bind to oxygen atom and break O-O bond in the three-copper cluster through a four electron transfer process. Heme containing oxidases and oxygenases (HCOs) employ protonporphyrin IX coordinated iron (usually in six-coordinated state with one axils ligand) as the active center. The axils ligand facilitates the process of oxygen binding to Fe active site and O-O bond cleavage, while the mechanism varies in peroxidases and oxygenases. Non-heme oxidases and oxygenases (NHOs) also use iron as the active center, but iron is usually coordinated to amino acid residues instead of protonporphyrin IX ligand. Some progress on synthesis of biomimetic catalyst was also reviewed. Not only the active site but also the supporting media are demonstrated to affect the catalytic activity and reusability of the artificial enzymes. This review would provide useful information for enzyme application and design of biomimetic catalyst.