The invention relates to a multicomponent composition for photodegradable and biodegradable plastic articles, and the use of said composition in the manufacture of various disposable and packaging plastic articles and the articles made therefrom. The multicomponent composition does not contain starch, and is a multicomponent compounded composition of new bioactive material of chitin, casein and the like, with biodegradable aid component, photodegradable and auto-oxidation catalysis component, and nonmetallic minerals and the like. Under natural condition, the degraded material can be utilized by microorganism to release carbon dioxide and water, and acts as an eco-friendly plastic material.