To clarify nutrient release characteristics of sheep manure organic fertilizer and provide theoretical basis for applying sheep manure organic fertilizer in hilly tobacco drylands of western Henan, nylon mesh bag in situ culture experiment was conducted in 2019 to study carbon and nitrogen mineralization characteristics of decomposed sheep manure organic fertilizer as well as its effects on soil available nutrient contents and humic acid composition in Luoyang tobacco drylands, in which sheep manure organic fertilizer was buried in soil ridging before tobacco seedlings were transplanted. The results show that the mineralization of sheep manure organic fertilizer is slow in 0-15 days but fast after 15 days, and mineralization rate reaches the peak at the 75 day (the mineralization rates of carbon and nitrogen are accounted for 87.81% and 88.11% of the total mineralization during the whole mineralization period), then decreases and stabilizes. With the increase of buried days, the contents of soil nitrate nitrogen, available phosphorus and potassium are increased, while the content of soil ammonium nitrogen is decreased, indicating that the mineralization process of sheep manure organic fertilizer is beneficial to promote soil nitrification and enhance nutrient supply capacity of soil. Sheep manure organic fertilizer also promotes the formation and accumulation of humus acid in soil. After 60 days of application, the contents of soil humic acid, fulvic acid and humic acid and the ratio of H/F are significantly higher than those of the control treatment. Therefore, carbon and nitrogen mineralization are in good agreement with the fertilizer requirements of flue-cured tobacco, which are also beneficial to improve soil quality when sheep manure organic fertilizer is applied before transplanting of flue-cured tobacco seedlings in the drylands of western Henan Province, but mineralization rate of sheep manure is slow in the early stage thus should be combined with chemical fertilizer.