The present disclosure relates to a pharmaceutical composition for preventing or treating respiratory diseases and a food composition for preventing or relieving respiratory diseases comprising a mixed extract of Dioscoreae Rhizoma, Taraxaci Herba and Schizonepetae Spica as an active ingredient. A composition comprising a mixed extract of Dioscoreae Rhizoma, Taraxaci Herba and Schizonepetae Spica of the present disclosure has an advantage of preventing respiratory diseases and relieving the symptoms of respiratory diseases, restores damages in the lung tissue and has efficacy for inhibiting inflammation, oxidative stress and ageing reactions induced by fine dust. More particularly, the composition of the present disclosure increases the expression of a telomerase which extends the length of a telomere, and thus is expected to fundamentally treat degenerative respiratory diseases induced by fine dust unlike existing symptom alleviating agents.