We report on a plasma electrolytic oxidation (PEO)-treated Mg-Zn-Ca-Si amorphous alloy composite with enhancement of plasticity and corrosion resistance. The coated composite material exhibits excellent mechanical properties in compression, with a large plastic strain of 11.2% and a high fracture strength of 709��MPa. The enhanced plasticity may mainly ascribe to the partial nanocrystallization of amorphous phase in composite during PEO process, which can not only prevent runway localized plastic flow due to work softening, but also can introduce nucleation sites for the bands resulting from stress mismatch and compositional heterogeneity. Moreover, comparing with bare amorphous alloy composite, the corrosion current density measured in stimulated body fluid for the PEO-treated specimen decreases from 1.08 �� 10���3 to 4.45 �� 10���7 A/cm2. The present study may provide a fundamental basis for developing high-performance biodegradable Mg alloys.Please check the edit made in the article title.Yes, I have checked. There is no problem.