Abstract: During bioassay for the fat-soluble allelochemicals,we generally use common organic solvents such as ethanol etc.to solubilize the fat-soluble substances,for the method,it easily causes toxic effects on seeds and influence accuracy of the bioassay.On the principle of pharmacy,poloxamer (F-68) is adopted in our research,which is a kind of surfactant used in animal and cytological experiments,as a solubilizer to the experiment of fat-soluble allelochemicals bioassay.We compared the activity of vanillin and ferulic acid with two methods of the poloxamer and ethanol solution in general.The result showed that the concentration of allelochemicals solution processed by poloxamer had no change in quantitative detection of allelopathy activity,and no harmful effect on seed germination and seedling growth,and making for quantitative studies to the activity of allelochemicals.In contrast with ethanol groups,we found that the activity of allelochemicals has been strengthened,or weakened which caused by over concentration from ethanol volatile,to the extent that the allelochmicals crystallized from the solution.The research indicated that the method which the allelochemicals processed by poloxamer has adventages than the general method in fat-soluble allelochemicals.