The invention relates to a method and a device used for generating gas samples with specific humidity. The method comprises following steps: 1, original gas is introduced into a gas storage tank, andthe humidity of the original gas id detected; 2, when the humidity of the original gas is lower than that of a target gas sample, the mass amount of lacked water of the original gas is calculated; when the humidity of the original gas is higher than that of the target gas sample, the original gas is delivered through a drying unit to reduce the humidity of the original gas to be lower than that ofthe target gas sample, and the mass amount of lacked water of the original gas is calculated; 3, the certain mass amount of water is introduced into a humidification processing unit. The method and the device are capable of reducing steps including drying, humidifying, and mixing at certain ratios of the original gas, and increasing the efficiency of generation of gas samples with specific humidity.