The complicated fibrousnetwork structure of lignocellulose has adverse impact on the starting time of biomass dry anaerobic digestion. According to the pyrolytic properties of lignin, thermochemical pretreatment by using fluidized bed was put forward to pretreat the biomass. The present work was aim to investigate the influences of the thermochemical pretreatment technique on the biogas production via biomass dry anaerobic digestion. Experiments for the biogas production via biomass dry anaerobic digestion using the corn stalk samples treated at 150℃, 170℃, 190℃, 210℃ in a fluidized bed and untreated sample were carried out at 35℃ for 42d, respectively. Obviously, the results showed that thermochemical pretreatment could change the fibrousnetwork structure of lignocellulose. It resulted 5.98%~22.25% and 1.75%~20.99% decrease on hemicellulose and lignin, and enhanced the methane production ranging in a certain temperature. The digestion time T80 mirrored the efficiency of fermentation, 190℃ and 210℃ pretreatments got the shortest digestion time which were shorter 3d than the untreated of 30d. The highest methane yield of 30d was obtained at 190℃ pretreatment biomass sample which was 16.30% higher and the startup time was 2.10d less than the untreated. Other pretreatments also improved the methane yield by 1.67%~9.78% and resulted the startup time less than the untreated. Although 210℃ pretreatment could destroy the structure of lignocellulose more seriously, it also led methane production reduction due to the more wastage of hemicellulose and cellulose. The conclusions could be made that thermochemical pretreatment technique is one of the effective methods to improve the methane production and accelerate the startup time of dry anaerobic digestion observably.