Abstract:In order to understand the controlling effect of winter wheat straw incorporated into soil on root- knot nematode disease (RKN, Meloidogyne spp.), an in-door pot experiment was conducted in greenhouse for six months, with three treatments of different addition of wheat straw into the soil and tomato was taken as the experimental crop. The results indicated that RKN could be suppressed by adding wheat straw into the soil, and the suppression rate of RKN in the three treatments of 1N (straw 2.08g/kg soil), 2N (straw 4.16 g/kg soil) and 4N (straw 8.32 g/kg soil) were 51.4%, 940%, 39.5% respectively. However, over dose of straw input would cause negative effect on tomato growth. The plant height, stalk diameter and flowering rate significantly decreased at the straw addition of 8.32 g/kg soil (4N), but decreased much less at the straw addition of 1N (straw 2.08g/kg soil) and 2N (straw 4.16 g/kg soil).The results also showed that the soil nematode community changed after the introduction of wheat straw carbon resources, with herbivores nematodes decreasing and bacterivores, fungivores and omnivores-predator nematodes increasing in all treatments. In 1N, 2N and 4N treatments, the herbivores nematodes decreased 17.6%, 97.3% and 2.0%, respectively; and the bacterivores nematodes increased 100.5%, 189.7% and 117.8%, respectively. For these two dominant functional groups, the 2N treatment caused the biggest change of soil nematode community structure. In 4N treatment, fungivores nematodes increased 350%, showing a remarkable increment direction; while omnivores-predator nematodes increased the most obviously in 1N treatment, which was 66.7%. Considering tomato growth situation, suppression rate on RKN and changes of soil nematode community structure, the controlling effect of addition winter wheat straw into soil on RKN was the best at the straw addition of 2N (straw 4.16 g/kg soil).