NOVELTY - Power generation by collecting and purifying landfill gas comprises: building a gas collecting shaft, collecting gas by means of the gas collecting shaft, and processing the collected landfill gas into combustible gas as required by a power station.    USE - The method is useful for power generation by collecting and purifying landfill gas (claimed).    DETAILED DESCRIPTION - Power generation by collecting and purifying landfill gas comprises: building a gas collecting shaft, collecting gas by means of the gas collecting shaft, and processing the collected landfill gas into combustible gas as required by a power station, where the construction of the gas collecting shaft comprises the steps as follows: (a) by the gravity of a grab bucket, building a shaft by borehole, where if the liquid level of refuse leachate is higher than a preset value in the building, the grab bucket is provided with a drainer for reducing the liquid level under the preset value; (b) not cyclically repeating step (a) until the gas collecting shaft obtains a preset height; (c) mounting a shaft pipeline, and mounting a gas collecting pipe on the part of the shaft pipeline above the ground; (d) mounting a refuse leachate drainage pipe in the shaft pipeline, so the lower mouth of the drainage pipeline is 0.2-0.5m distant from the shaft bottom; (e) setting an apparatus at the inner bottom of the drainage pipe of refuse leachate, which can generate tiny bubbles whose average diameter is within 20-40 microns, and mounting a compressed air pipe of the apparatus; (f) mounting a shaft mouth sealing plate on the shaft mouth, which has two insert holes for the drainage pipe and compressed air pipe in advance; and (g) divisionally connecting all the gas collecting pipes of the gas collecting shaft of a refuse landfill to several gas collecting stations, where all the gas collecting pipes are separately provided with a valve; the gas collecting comprises: detecting methane content and oxygen content of each gas collecting shaft in real time, and closing the relative gas collecting pipe in the case that oxygen content is higher than 2%, feeding gas to from the relative gas collecting pipes to a main gas-collecting pipe in the case that oxygen content is lower than 2% and methane content is higher than 50%, thereafter, closing the gas collecting pipes in the case that methane content is lower than 4%; the landfill gas processing comprises: buffering the landfill gas at first for supplying the consequent steps with gases of stable pressure, flow rate and methane content, thereafter, eliminating sulfurated hydrogen lower than 20mg/Nm3 by three-stage quick dry method, dedusting the desulfurated gases by spraying so that the diameter of the grains is smaller than 5 microns and the content is lower than 30mg/Nm3, and then lyophilizing the gases so as to control the water content lower than 20mg/Nm3, finally, increasing the pressure of the gases to 15-20KPa, and then feeding them to a generating set for power generation.