L-threonine is an essential amino acid in human and animal nutrition. It is widely used in food, medicine, feed, and other fields. The global market scale exceeds 700,000 tons per year. Corynebacterium glutamicum, as a chassis cell for industrial amino acid production, has the advantages of biological safety and strong environmental adaptability, and is a potential strain for the efficient production of l-threonine. This article systematically reviewed the function and application of l-threonine, the pathway of C. glutamicum to synthesize l-threonine, and the use of metabolic engineering technology to improve the production of l-threonine.