NOVELTY - Improving gas production property by mixing and approximately synchronous fermentation synergistic effect of multiple raw materials, comprises physically crushing organic solid wastes, crushing kitchen substance, fruits and vegetables into fluid slag, pre-treating by sodium hydroxide (NaOH) solution, fully mixing the pre-treated straw and excrement, placing the mixture into an anaerobic digestion reactor, adding inoculating sludge, and fully stirring to homogenize the material.    USE - The method is used for improving gas production property by mixing and approximately synchronous fermentation synergistic effect of multiple raw materials (claimed).    ADVANTAGE - The method above is simple and has strong operability, where two or more of organic solid wastes are treated. The accumulated gas production of the unit VS (volatile solid) substance can be improved for 15-60% on the average.    DETAILED DESCRIPTION - Improving gas production property by mixing and approximately synchronous fermentation synergistic effect of multiple raw materials, comprises physically crushing organic solid wastes, crushing kitchen substance, fruits and vegetables into fluid slag, crushing straw to 1-5 cm, pre-treating by NaOH solution with the mass concentration of 2% for 3 days, fully mixing the pre-treated straw and excrement according to dry substance TS mass ratio of 0.4:1-6:1, where the dry substance is substance of fresh raw material without the moisture, and the following proportions are dry substance TS mass ratio if no description; placing the mixture into an anaerobic digestion reactor, adding inoculating sludge, which is digestion sludge of a sewage treatment plant or a methane station with stable operation, pH value is 7.0-8.0 and ammonium nitrogen value is 100-800 mg/L, fully stirring to homogenize the material, where the adding amount of the inoculating sludge is 10000-20000 mg/L, the mass is based on TS, and the volume is working volume of the reactor; adding water to fix volume until the concentration of the substance in the reactor is 20-80 gTS/L, closing the anaerobic digestion reactor, connecting the air outlet of the reactor with a device for metering methanol by a gas transmission pipe, controlling the reaction temperature to 35 plus minus 2 degrees C centigrade, stirring in an anaerobic digestion process, and generating methane in 12 hours; or mixing fruit, vegetable, kitchen substance and inoculating sludge to carry out anaerobic fermentation, centrifuging the fruit, vegetable and inoculating sludge, dropping supernate, fully mixing in the anaerobic digestion reactor according to a proportion of 14:5-11:1 to carry out anaerobic fermentation, where the adding amount of the sludge is 10000-20000 mg/L, adding water and fixing volume to cause the concentration of the substance in the reactor to 20-60 gTS/L, closing the anaerobic digestion reactor, stirring in an anaerobic digestion process, and generating methane in 12 hours.