Abstract: Maize straw residue was decomposed under laboratory conditions,and filtered at different time. Phenolic acids was measured by HPLC. The effects of phenolic acids on spore bourgeon and mycelial growth of pathogens of winter wheat soil-borne disease were tasted. The results showed that five kinds of phenolic acids were discovered in decomposing products of maize straw, the types and contents of phenolic acids were different in the decomposing products of different periods, Pathalic acid and Frulic acid in the decomposed liquid filtered at the same time are higher than other three kinds of phenolic acids ; the three kinds of pathogens and the bourgeoning of G.graminis and B.sorokiniana were accelerated and restrained by five kinds of phenolic acids, and the process was stronger with the increase of concentration.