Abstract: Heat acclimation (at 38 ℃) or foliage spraying with 100 μmol/L salicylic acid (SA) was conducted in young plants of grape （Vitis vinifera cv.Jingxiu）. The results showed that similar changes of the content of abscisic acid (ABA) in plants were induced by SA spraying or heat acclimation. The content of ABA were drastically increased after 1h of two treatments, then significantly declined, no obvious changes occurred after then. The change trend of lipoxygenase （LOX） activity differed from ABA. When grape plants were acclimated at 38 ℃, variation of free SA content and ABA content in leaves were similar. Change trend of phenylalanine ammonia lyase (PAL) activity was similar to that of free SA.It indicated that SA was likely a chemical signal molecule. We suppose that SA induced thermotolerance of grape seedlings solely or through ABA.