Biogas slurry was known to affect the soil-plant ecosystem when applied as manure, especially in combination with chemical fertilizer. However, little knowledge was available regarding how this combination affects peanut yield and soil fertility in peanut fields of red soil, South China. Therefore, a two-year field experiment, designed to have 6 treatments, except for CK (No fertilizer applied), different in proportion of biogas slurry N to total N input [0% (NPK), 15% (BS15), 30% (BS30), 45% (BS45) and 100% (BS100)] and the same in NPK rate (N-P2O5-K2O, 120-90-135 kg hm-2), was carried out to evaluated synthetically the effects of combined application of biogas slurry and chemical fertilizer on peanut yield, soil organic matter, labile organic matter, carbon management index and soil nutrients (N, P, K et al) in the Red Soil Ecological Experiment Station, Chinese Academy of Sciences. Results show that combined application increased peanut yield by 33.2%～48.3% and 10.2%～22.8% as compared to that in CK and Treatment NPK, respectively, with Treatment BS30 in particular, reaching 3332 kg hm^-2 in peanut yield or being 4.0%～48.3% higher than the other treatments, separately. Meanwhile it also significantly increased soil organic matter, labile organic matter and carbon management index (CMI), and the effect was especially obvious in Treatment BS30. The findings suggest that combined application may increase the content of soil organic matter and improve its quality as well. Treatment BS30 markedly increased soil total nitrogen, ammonium nitrogen, nitrate nitrogen, available phosphorus and potassium in the soil, as compared with CK and Treatment NPK, respectively. Correlation analysis of peanut yield with soil nutrients (N, P, K, etc.) reveals that its correlation coefficient was the highest with available phosphorus, being 0.956**, which indicates that soil available phosphorus is presently the main factor affecting peanut yield in peanut fields of red soil. In addition, peanut yield was also found positively related to labile organic matter with correlation coefficient being 0.826*, but did not have much to do with organic matter. At the same time, labile organic matter was in extremely significant or significant positive relationship with organic matter (0.920**), total nitrogen (0.894*), total phosphorus (0.867*), available phosphorus (0.872*) and available potassium (0.821*), while organic matter was significantly related only to labile organic matter (0.920**), total nitrogen (0.922**) and available phosphorus (0.862*), which suggests that labile organic matter could be better used as indicator of soil quality than organic matter, and, hence, may well be used as a good index for evaluation of soil fertilization efficiency. All the findings in this experiment indicate that the combined application of biogas slurry and chemical fertilizer, 3:7 in ratio can not only significantly increase peanut yield and reduce the use of chemical fertilizer, but also build up the soil nutrient pool with higher labile organic matter and organic matter contents. It is, therefore considered to be an effective way to increase peanut yield, while building up soil fertility in the upland red soil areas of South China.