Biogas production from the co-digestion of highland barley straw (BS) with Tibet pig manure (TPM) and cow manure (CM) was investigated at Tibet plateau under low temperature (15<SUP>o</SUP>C) condition. The effect of inoculum to substrate (I/S) ratio and BS to manure ratio on the biogas production was studied using a series of batch digesters performed at substrate concentration of 20%, based on total solid (TS). The results showed that biogas production from BS was feasible at low temperature and low air pressure condition. High I/S ratio (>2/1) and BS to manure ratio of 1/1 could increase the biogas production. Long solid retention time (SRT) (>80days) was needed for biogas production at low temperature and low air pressure condition. The highest cumulative biogas production obtained from the co-digestion of BS with TPM and CM was 233.4ml/gVS and 192.0ml/gVS, respectively. Removal efficiencies of substrate showed that biogas production was correlated with the removal efficiency of water-insoluble volatile solids (IVS) but not with the change rate of soluble chemical oxygen demand (SCOD).