Abstract: Batch experiments were conducted to investigate the effects of different oil and salt concentrations on removal efficiency of organic matter, methane production and microbial community succession by controlling the amount of blended oil and sodium chloride during anaerobic digestion of simulated food wastewater under moderate temperature conditions (35 ℃). The results showed that compared to the control group without oil and salt, the addition of oil (8 g/L and 10 g/L) and salt (9 g/L and 12 g/L) caused the deterioration of the system. Nevertheless, the 8 g/L oil and 9 g/L salt co-occurrence can alleviate the stress effect of oil or salt. Compared to the experimental group with the same content of oil or salt alone, methane production of 8 g/L oil and 9 g/L salt co-occurrence experimental group increased by 28.76% and 30.45%, respectively, which may be due to the fact that oil and its degradation products long chain fatty acids (LCFAs) wrapped on the cell surface as a buffer of high osmotic pressure, while binding Na⁺ and Ca²⁺ to form precipitations, thus weakening the harm of Na⁺ and LCFAs. The system enriched the glucose-degrading bacteria including Actinomycetes, Methanosaeta and Methanobacterium, thereby increasing methane production. Compared to the oil and salt group alone, the reduction in methane production was more pronounced after further increasing the concentration of oil and salt co-occurrence (e.g., 8 g/L oil and 12 g/L salt or 10 g/L oil and 9 g/L salt), which might be due to the fact that Na⁺ induced cell rupture and enzyme inactivation could not be alleviated by the buffering effect of oil. In addition, the abundance of Actinomycetes and methanogens decreased, inhibiting organic methanation. Therefore, the co-occurrence of 8 g/L oil and 9 g/L salt can alleviate the inhibition of oil and salt alone, which can provide theoretical basis for the condition control of anaerobic digestion methane production process of food wastewater with high content of oil and salt.