summaryTo investigate the effect of the ratio of pig manure (PM) to rice straw (RS) and the total solid (TS) concentration of the feed on anaerobic methane production under medium temperature conditions, batch anaerobic fermentation experiments were conducted to determine the raw material ratio under different volatile solid (VS) ratios (PM: RS=1:0, 4:1, 2:1, 1:1, 1:2, 1:4, 0:1). The mixed raw materials with VS ratios (PM: RS=1:1, 4:1) were selected for continuous anaerobic fermentation experiments with gradient increase in feed concentration (TS=4.6%, 7.1%, 9.6%, 12.1%). The sentence is:. The results showed that in batch fermentation experiments, the methane production performance of VS PM: RS=4:1 was evaluatedbetterThe methane production potential (P value), reaction kinetics constant (k), high methane rate (R m), and arrival time (t max) are 380.3 mL  g -1 VS, 0.098 d -1, 37.2 mL  g -1 VS  d -1, and 4.4 d, respectively. When the hydraulic retention time is 30 days, the continuous methane production performance of VS PM: RS=4:1 is better. When the feed concentration reaches 12.1%, the methane yield, methane production potential conversion rate, and volumetric methane production rate reach 354.8 mL  g -1 VS, 93.3%, and 0.88 L  L -1  d -1, respectively. But the higher the proportion of pig manure in the mixed material, the higher the risk of ammonia inhibition in the fermentation system. When the feed concentration reaches 12.1%, the free ammonia concentration of VS PM: RS=4:1 is 1.47 times that of VS PM: RS=1:1, reaching 223.2mg  L -1. Research has shown that when pig manure and rice straw are mixed as raw materials VS PM: RS=4:1 (with a C/N ratio of 22-23:1), the conversion efficiency and volumetric methane production rate of fermentation materials can be improved; At the same time, a TS concentration of less than 12.1% (OLR of 2.87 g VS · L -1 · d -1) can reduce ammonia inhibition in anaerobic fermentation and ensure stable operation of biogas projects.