The present invention relates to a method of producing high-quality reduced coenzyme Q 10 converted from oxidized coenzyme Q 10 by natural reductase. It is stable, completely natural, and can be used for injection. This method is suitable for large-scale industrial production without special protective environment/atmosphere. The method of producing reduced coenzyme Q 10 includes three stages: (1) phosphorylation of oxidized coenzyme Q 10 (2) reduction of phosphorylated oxidized coenzyme Q 10 by biological reductases (3) extracting reduced coenzyme Q 10 from reductases,
