The symptoms of Atractylodes chinensis in Moqi area, Inner Mongolia were described. Ten isolates with identical morphology were obtained by tissue isolation and single hyphae purification. Pathogenicity of ten isolates were confirmed by Koch’s Rule. The pathogen was determined to be caused by the Rhizoctonia Solani AG1-1 B fusion group by combining morphological characteristics and rDNA-ITS sequence analysis. When pH is 8, it is the most suitable for mycelia growth, and the light condition has no influence on the growth of mycelia. The lethal temperature and time of mycelia were 48℃ and 10 min, respectively. The sensitivity of the pathogen to 27 fungicides was determined by growth rate method. The pathogen was more sensitive to 430 g/L Tebuconazole SC, 25% Trifloxystrobin · 50% Tebuconazole WG, 5% Pyraclostrobin · 55% metiram WG, EC₅₀＜0.1 mg/L. The sensitivity of 40% Dimetachlone WP, 10% Polyoxin WP, 40% Flusilazole EC, 25% Pyraclostrobin EC, 10% Difenoconazole WG,50% Carbendazim WP, 75% Chlorothalonil WP, 50% Procymidone WP, 250 g/L Azoxystrobin SC, 10% Metalaxyl ·48% Mancozeb WP, 50% Triflumizole WP was followed by with 0.1 mg/L＜EC₅₀＜1 mg/L.