Abstract: Effects of dissolved organic matter (DOM), extracted from earthworm casts and cattle manure, on the ryegrass growth were studied under hydroponics condition. There were five treatments of two different concentration of DOM extracted from earthworm casts and cattle manure (10g earthworm casts or cattle manure DOM, 20g earthworm casts or cattle manure DOM) and the control, The results show that DOM extracted from earthworm casts significantly increased biomass of shoots and roots of ryegrass, and length, surface area, volume, and number of tips of the root system (p＜0.05); the growth of the root was promoted more significantly than the shoot; each indicator reached the maximum quantity under the treatment of 20 g earthworm casts DOM, which explained that the earthworm casts DOM significantly promote the ryegrass growth than cattle manure DOM. In addition, the high concentration of DOM had better effects on the ryegrass growth than the low concentration of DOM. Overall, it could be inferred that the earthworm casts DOM significantly promote the growth of plants.