Landfill gas is generated by organic waste decomposing under anaerobic conditions. landfill gas contributes to the emission in the atmosphere of greenhouse gases and causing global warming. Humidity of environment is an effective parameter on rate of gas generation in landfills. Saravan landfill is investigated as study area in this research. It located in 20 kilometers of Rasht-Tehran highway. It is modeled as an anaerobic landfill within dry and moist condition in landGEM software and amount of gas emissions in calculated per year. Results of the study show the rate of gas generation in moist condition is 3.85 times of dry condition. In Saravan landfill ,the maximum generation rate of methane,carbon dioxide and Non-methane Volatile Organic Compounds (NMVOCs) was 11700, 32110 and 500 Ton/Year in moist condition and 3043, 8349, 130 Ton/Year in dry condition, respectively.In regard to effect of moist on rate of contaminants generation and humidity of the study area, using the cap as a contaminants control methods is assessed. We suggested multiple cap for the landfill. The cap caused oxidation of methane and prevent of moist into landfill, then it reduce the rate of gas and leachate generation. The designed cap has inactive gas collection and leachated drainage systems.