Trichoderma species are naturally occurring soil fungi which are used for control of crop diseases by promoting plant growth and inducing plant resistance to abiotic and biotic stresses.Peppermint (Mentha piperita L.) is an important and commonly used flavoring agent worldwide.Here the effects of Trichoderma harzianum LTR-2 on the salt tolerance and essential oils (EOs) production of peppermint were investigated.On one hand, results of salt tolerance analysis showed that LTR-2 effectively alleviated the growth inhibition and photosynthetic damage of peppermint under 200 mmol/L NaCI treatment.LTR-2 conferred the enhanced tolerance of peppermint to NaCl stress through increasing antioxidant activities to eliminate ROS accumulation and up-regulating the activities of plasma membrane (PM) and vacuolar H+-ATPase and Na+/H+ antiporter to regulate the absorption and distribution of ions.