The objective of this work was to investigate the performance and archaeal community of methanogenic digester under different temperatures (35°C, 55°C) and pH values (6.5, 7.0, 7.5, 8.0 and 8.5) in two-phase anaerobic digestion of pig manure and maize straw. The specific CH4 yields decreased by 22.6%, 60.0% and 94.1% for pH 7.5, 8.0 and 8.5 compared with pH 7.0 (277 N mLg-1CODadd) at 35°C, and decreased by 31.6%, 70.9% and 95.0% compared with pH 7.0 (253 N mLg-1CODadd) at 55°C The methane productions of mesophilic digestion at five pH levels were 13.6%, 9.7%, 24.1%, 50.8% and 30.0% higher than that of thermophilic digestion. Terminal restriction fragment length polymorphism (T-RFLP) analyses combined with clone library indicated that Methanosaeta and Methanosarcina were the dominant genus at 35°C and 55°C, respectively, and the relative abundance decreased significantly with the pH increasing from 7.5 to 8.5.