Disclosed herein is a method of controlling the landfill gas generation within the landfill in which leachate is recycled to be continuously injected into a deposit of wastes while extracting the landfill gas from a landfill gas extraction pipe inserted into the waste deposit, comprising steps of: (a) maintaining the recycling leachate at the temperature range of 35.degree. C. to 38.degree. C. and/or the pH of 6.5 to 7.5 until the amount of generated landfill gas reaches from the range of 5% to 20% of a capability of the landfill gas generation in the landfill; (b) maintaining the recycling leachate at the temperature range of 30.degree. C. to 35.degree. C. or the range of 60.degree. C. to 65.degree. C. and/or the pH of 6 to 7 until the amount of generated landfill gas reaches from the range of 75% to 90% of a capability of the landfill gas generation in the landfill; and (c) maintaining the recycling leachate at the temperature range of 35.degree. C. to 38.degree. C. or the range of 50.degree. C. to 54.degree. C. and/or the pH of 6.5 to 8.0 until the amount of generated landfill gas reaches to 100% of a capability of the landfill gas generation in the landfill.