Abstract: By using ELISA technology, we studied effects of fulvic acid (FA) on IAA and ABA levels in leaves of winter wheat seedlings. The result indicated that FA could increase IAA and ABA levels, which is consistant with FA’ s effects of stimulating plant growth and inhibiting stomatal opening, and FA had no synergy both with IAA and ABA. So we concluded that FA could act on plant directly, and could also act on plant indirectly by changing levels of endogenous phytohormones.