Abstract: To find a new effective and low toxic method of prevention and cure Meloidogyne incognito, the methanol extracts from leaves of Cynanchum komarovii were investigated by toxicity test and potting experiment. The results showed that the methanol extracts from leaves of Cynanchum komarovii could highly control Meloidogyne incognita. The treatment (concentration: 3000mg/L, treatment time:48h)，which could lead to 93.30% of corrected mortality for Meloidogyne incognita, had the strongest bioactivity with LC50 of 418.7mg/L, among all the treatments. The Meloidogyne incognita was treated with the methanol extracts from leaves of Cynanchum komarovii which were diluted 100 times, 1000 times and 5000 times respectively. The results showed that the average numbers of root-knots were 11.4±2.24, 24.6±3.78 and 41.2±4.46, which were significantly lower than the control of 5% methanol (67.5±6.18), the plant height of tomato increased 26.5%, 18.7% and 6.6%, the fresh mass increased 31.4%, 12.7% and 1.5% , and the length of root increased 32.6%, 28.8% and 20.9% compared with the control respectively. The methanol extracts of Cynanchum komarovii can alleviate the harm of Meloidogyne incognita and promote the growth of plant. Further research should be done for utilizing Cynanchum komarovii to control Meloidogyne incognita.