The present invention provides a method of enhancing hyaluronic acid secretion in a subject, which comprises administrating a composition containing of Streptococcus thermophilus DSM 28121 to the subject, and the hyaluronic acid content in the blood of the subject is increased. The present invention further provides a novel probiotic strain which is Streptococcus thermophilus DSM 28121, which has the ability to survive and colonize in the intestine of the subject to increase the number.