Abstract: Abstract: This experiment used two kinds of phenolic acid and its mixture in different concentration to carry on seed and seedling of the wild oat, and studied the effects of the germination rate, the morphological parameter and some physiological parameters of seedling. The result indicated that the phenolic acid and its mixture could defer the remarkable time of wild oat seed germination, reduce seed germination rate, inhibit the physiological parameter and accumulated amount of dry matter to a certain extent, decrease the Root activity and chlorophyll content inordinately, and increase malondialdehyde level in seedling.