Abstract: In order to provide theoretical basis to solve continuous cropping obstacles of pepper, the allelopathic autotoxicity of pepper root exudates collected by different methods was studied. The root exudate of pepper was collected through nutrient solution culture and sand culture, and the allelopathic autotoxicity was studied by the method of bioassay. The results showed that the pepper root exudates collected by nutrient solution culture could significantly inhibit the seed germination and seedling growth, and the highest inhibition effect could be achieved at the concentration of 30 g/L, the allelopathy autotoxicity of‘Rela No.2’root exudates on seed germination was higher than that of‘Retian No.5’, but the allelopathy autotoxicity of‘Retian No.5’root exudates on seedling growth was higher than that of‘Rela No.2’. The pepper root exudates collected by sand culture could significantly inhibit the seed germination and seedling growth, and the inhibiting effect increased with the increase of root exudates concentrations and also reached the highest at the concentration of 30 g/L, the comprehensive allelopathy autotoxicity of‘Rela No.2’root exudates was higher than that of‘Retian No.5’. The root exudates of pepper had allelopathic autotoxicity effect on seed germination and seedling growth. Therefore, root exudates of continuous cropping pepper accumulated year by year had autotoxicity, and it might be the important reason leading to continuous cropping obstacles of pepper.