Autotoxicity is a specific form of allelopathy that causes a reduction in growth of individuals of the same species via the release of chemical substances into the soil or nutrient solution. Autotoxicity effects often are manifested as reduction in crop yield and difficulty with re-establishment of plants in fields because of low seed germination and poor seedling growth. Phenolic acids are important autotoxic compounds that hinder continuous cropping and thus their phytotoxicity has been studied intensively. By means of pot experiments, the autotoxicity of aqueous extracts from peanut plants and rhizospheric soil on germination and growth of peanut seedlings was tested. The phenolic acids in peanut rhizospheric soil, subject to rotational cropping or, continuous cropping for 2, 4 and 6 years, were qualitatively and quantitatively analyzed with high-performance liquid chromatography (HPLC). Differences between treatments were analyzed by one-way ANOVA and Duncan's new multiple range test. The aqueous extracts from different plant parts and rhizospheric soil inhibited seed germination to different degrees, and showed a concentration gradient effect on the inhibition of seed germination. Inhibition was stronger with increased extract concentration, and the inhibitory effect was highest at 16 parts aqueous extract to 10 parts deionized water (16 g/10 mL). At the lowest extract concentration of 4 g/10 mL, the seed germination percentage in the presence of soil, stem and leaf extracts was 60%, 63% and 68%, respectively; the germination energy was 35%, 12% and 12%; the germination index was 2.67, 2.14 and 2.3; and the root length was 2.11 cm, 1.97 cm and 1.69 cm. At the highest extract concentration of 16 g/10 mL, the germination percentage of soil, stem and leaf extracts was 47%, 60% and 28%, respectively; the germination energy was 28%, 2% and 0; the germination index was 2.09, 1.84 and 0.86; and the root length was 1.83 cm, 1.54 cm and 1.31 cm. The aqueous extracts showed different degrees of inhibition on plant growth, and an extract concentration gradient effect on growth inhibition was observed. Inhibition was stronger with increased extract concentration, and the inhibitory effect was highest with the 16 g/10 mL aqueous extracts. At the lowest extract concentration of 4 g/10 mL, plant height in the presence of soil, stem and leaf extracts was 10.70 cm, 12.59 cm and 17.26 cm, respectively; the root length was 18.58 cm, 14.78 cm and 15.67 cm; the plant fresh weight was 2.86 g, 3.98 g and 5.77 g; the plant dry weight was 0.84 g, 0.90 g and 0.96 g; and the leaf area was 12.01 cm², 16.10 cm² and 28.55 cm². At the highest extract concentration of 16 g/10 mL, the plant height in the presence of soil, stem and leaf extracts was 9.92 cm, 12.03 cm and 16.10 cm, respectively; the root length was 15.60 cm, 14.32 cm and 14.72 cm; the plant fresh weight was 2.68 g, 3.86 g and 5.50 g; the plant dry weight was 0.71 g, 0.80 g and 0.84 g; and the leaf area was 11.04 cm², 12.62 cm² and 26.10 cm². Peanut growth was affected by the presence of the autotoxic substances, and the impact on growth varied among aqueous extracts from different plant parts. The autotoxicity of stem aqueous extracts had the most significant impact on seed germination, plant height and leaf area. The autotoxicity of rhizospheric soil aqueous extracts had the most significant impact on plant root length, and plant fresh and dry weights. Four phenolic acids (p-hydroxybenzoic acid, vanillic acid, coumaric acid and coumarin) were detected in the rhizospheric soil extract and quantified by HPLC. Vanillic acid and coumarin contents were higher than those of the other phenolic acids and increased in concentration with number of years of continuous cropping. The amounts of vanillic acid and coumarin after cropping for 6 years were 0.289 μg/g dry soil and 0.025 μg/g dry soil, respectively.