Abstract: The objective of the research is to explore the effects and mechanisms of biochars on CO₂ emission from Loess Plateau alkaline farmland soil. Maize straw-derived biochars (BCs) were prepared at 400, 600 and 800℃, and their carbon skeletons (BS) were extracted by hot water. After analyzing the fundamental physicochemical properties of the six kinds of materials, each was thoroughly mixed with the soil by the mass ratios of 1% or 2%, and subsequently an indoor static soil incubation experiment was carried out for 50 days. The results show that pH value and the amount of total alkaline oxygen-containing functional group of BC and BS significantly increased with the pyrolysis temperature increasing from 400 to 800℃, while the contents of dissolved organic carbon (DOC), readily oxidized organic carbon (ROC) and the amount of total acidic oxygen-containing functional group significantly decreased (P < 0.05). The contents of DOC and ROC in the BS were significantly (P < 0.05) lower than that of BC produced at the same pyrolysis temperature. With the increase of the pyrolysis temperature of the added BC or BS, the cumulative CO₂ emissions of the treatments with BC or BS decreased. Moreover, the cumulative CO₂ emissions of the treatments with BC were higher than that with BS. Especially, the cumulative CO₂ emissions of BC-2% was significantly higher than that of BS-1% (P < 0.05). During the whole incubation, the contents of DOC and ROC in the amended soil decreased. However, the reduction extent of DOC (87.90%-89.18%) was greater than ROC (19.29%-38.49%). Moreover, both the contents of DOC and ROC show the following trend:BC-2% > BC-1%/BS-2% > BS-1% > Control during the incubation of the soil amended with BC or BS prepared at 400, 600 or 800℃. Additionally, the results show that DOC content could explain the variance of CO₂ emissions more than ROC in the treatments with BC or BS amendment (P < 0.01). DOC and ROC are the important factors affecting CO₂ emissions from Loess Plateau alkaline farmland soil. However, the impact of DOC on CO₂ emissions was more significant than ROC.