Biochemical methane potential (BMP) of fallen leaf and model kitchen garbage were tested after alkaline hydrothermal pretreatment to investigate the effects of thermal-chemical treatment on the digestibility of waste. pH of hydrolysate decreased after pretreatment, and organics were solubilized acceleratedly and hydrolyzed into low molecular products. Different optimum hydrothermal conditions were obtained for different waste. The BMP of leaf was observed when hydrothermal temperature was above 150 degrees C under alkaline condition, and SCOD concentration was 13 203 mg/L. Kitchen garbage was completely liquidized and suspended at 130 degrees C and SCOD concentration was 12412 mg/L, and addition of alkali show unobvious influence on methane production. Maximum specific methane yield were 112 mL/g VS and 276 mL/g respectively. The conversion rates on the basis of total carbon were 24.81% and 53.34%.