Objective: To explore the antibacterial and nematode resistant activities of Melia azedarach fruits and Melia azedarach barks. Methods: The crude extracts were prepared by Soxhlet extraction with 70% ethanol as solvent. Then the purified samples were dynamically adsorbed by S-8 macroporous resin; The antibacterial effect of the crude extracts of Melia azedarach fruits and Melia azedarach barks and their purified samples were determined by drilling method, and the MIC value of sensitive strains was determined by double dilution method; The half lethal concentration of Melia azedarach purified samples was determined by 96 well plate method. The results showed that the crude extract and purified sample of Melia azedarach barks had good antibacterial effect. The antibacterial effect of purified sample of Melia azedarach barks on the tested strains: Enterobacter cloacae > Salmonella enteritidis > Escherichia coli > Enterobacter aerogenes > Pseudomonas aeruginosa > Xanthomonas oryzae pv.oryzae > Pseudomonas solanacarum. The antibacterial effect of the crude extract of Melia azedarach barks was Escherichia coli > Enterobacter aerogenes > Salmonella enteritidis. The purified samples of Melia azedarach fruits and Melia azedarach barks had good killing effect on Caenorhabditis elegans, and the half lethal concentrations were 7 and 2.12 mg/ml respectively.