Abstract: Low quality and severe virus disease limit flue-cured tobacco production in the Loess Plateau of East Gansu Province. The effects of microbial organic fertilizer on tobacco growth, yield, quality and soil micro-organism were determined in a field trial. The field trial involved nursery and transplanted field cultivation where the effects of microbial organic fertilizer on local flue-cured tobacco production were investigated. Results showed that application of microbial organic fertilizer (T2) in nurseries significantly promoted tobacco growth and soil micro-organism population, which strengthened seeding vitality. Compared with T1 (chemical fertilizer), dry weight of max leaf and shoot increased respectively by 41.9% and 90.1% in T2. Total root length, specific root length, root dry weight and root tip number also increased by 151.5%, 25.8%, 100.0% and 286.0% in T2. Micro-organism count in T2 nursery soils increased. Specifically, actinomyce numbers rose significantly by 194.7% in T2 over T1, increasing disease resistance. Furthermore, T2 significantly promoted yield, quality and economic benefits of flue-cured tobacco in transplanted fields. Yield, economic benefit and net income increased respectively by 23.2%, 46.5% and 12 363 Yuan·hm^-2 in T2 over T1. Mid-high grade leaf ratio also increased by 16%. Main chemical components such as K, total N, nicotine, protein, sugar and schmuck were in the range of high-quality tobacco. Specifically, Middle-lower part leaf K content exceeded 3%, which signified high quality tobacco.