The effects of Jinggangmycin on the growth and development of Rhizoctonia solani Kühn causal agent of rice sheath blight,were investigated by using a virulent isolate GD-118 of R.solani as the test isolate. The results showed that the regression equation for Jinggangmycin toxicity to R.solani was: y=3.360 3+1.320 4x,correlation coefficient r=0.962 6,the EC50 for theoretical inhibition of mycelial growth was 70.2 μg/mL, and the EC95 was 6 341.5 μg/mL. In regarding to cultural characteristics and mycelial growth,compared with blank control (without Jinggangmycin), the colonies of Jinggangmycin treatments had relatively obvious characteristics of uneven edges with more dense mycelia and darkened colour in the plate; with the increase of Jinggangmycin concentrations, the dry weight of mycelia decreased, but the mycelial density on colony surface increased and the colour of colony darkened further. In regarding to sclerotial shape and distribution in the plate, the granular and brown sclerotia scattered on the colony surface of blank control, with more in the periphery and a few in the interior relatively; whereas most sclerotia in Jinggangmycin treatments were powdery, light brown, or a part of the sclerotia coalesced together to form blocks, distributed in the periphery of colony with obvious double rings and anomalous concave or convex edges. In addition,with the increase of Jinggangmycin concentrations,the dry weight of sclerotia increased,the emergence of sclerotia were about 24 h earlier than that of blank control. In regarding to the numbers of mycelial cell nuclei, with the increase of Jinggangmycin concentrations, the numbers of cell nuclei and their distribution in the plate increased abnormally.