Fusarium wilt is one of the main soil-borne diseases which are caused by Fusarium oxysporum and may infect a variety of crops. Since it spreads through soil, its traditional controlling methods, such as spraying fungicides, is quite limited in effect. In addition, excessive application of fungicide may not only contaminate the soil, but also affect quality of the agricultural produce. So a pot experiment was conducted to explore effect and mechanism of organic manure controlling Fusarium wilt. In the pot experiment, two types of organic manure, cow dung and bio-manure (bought from market), were used in the experiment. The manures were applied in two ways, base application as solid in soil and leafy application with liquid manure extract. Two sterilization status , sterilized and unsterilized, were also designed for manure and soil, and two sterilization methods were used, high pressure steaming and application of ClO₂, a kind of green fungicide, for manure and soil. A petri dish culture experiment was also carried out to study effect of organic manure controlling Fusarium oxysporum. Manure was also applied in two ways, solid and liquid manure extract. Solid manure was put in the center of the petri dish on the medium in the form of a granule, 0.2 g in weight. Manure extract, absorbed in a filter paper 2.75 cm in diameter, was also applied in the center of the petri dish on the medium. Four treatments in concentration of manure extract were designed. Two sterilization status, unsterilized and sterilized with high pressure steam, were also designed for solid manure and manure extracts. The treatment with no solid manure applied was set as control for comparison with the treatments applied with solid manure and the treatment applied with sterilized demi-water instead of manure extract was as control, too. Results show that organic manure may inhibit incidence of Fusarium wilt, though the effect is affected by a series of factors, such as type, application rate, application method and sterilization of the organic manure used, in an integrative way. The higher the application rate of organic manure, the higher the controlling effect. Application of cow dung and bio-manure at a rate of 1% and 5%, respectively, decreased the incidence of cucumber Fusarium wilt by 34.01%~36.80%, 50 days after seedling emergence. Base application decreased incidence of the disease by 66.82%~78.92% compared with leaf spray. Soil base application and leaf spray all decreased the incidence by 76.65%~81.17% and 17.11%~25.43% compared with the control. The disease controlling effect of organic manure was reduced by sterilization to such an extent that the incidence of cucumber Fusarium wilt increased by 18.27% and 82.82% over the treatments applied with non-sterilized manure at 1% and 5%, respectively and by 36.90% and 29.80% over control. In treatments with soil sterilized with ClO₂ organic manure reduced the disease incidence by 50%. Solid manure and manure extract could directly inhibit the pathogen of Fusarium wilt. A Fusarium oxysporum -free zone appeared like a circle around the manure particle or the filter paper saturated with manure extract. The higher the concentration of the manure extract, the better the controlling effects. The diameter of the pathogen-free zone expanded gradually with the incubation going in the solid manure treatments, but in the manure extract treatments the zone shrank gradually. Having been sterilized, both the solid manure and the manure extract did not show any inhibitory zone, which means that the manure lost its controlling effect on Fusarium oxysporum. The main mechanism of organic manure controlling cucumber Fusarium wilt may be explained as that organic manure enriches micro-organisms in the soil, thus directly inhibiting growth of the pathogen of Fusarium wilt. In addition, the chemicals or micro-organisms in the organic manure may also stimulate plants to improve their disease resistance.