Abstract: Gas detection devices comprise a dehydration unit a concentration unit, and a temperature control unit for controlling a temperature. The gas detection device includes a sampling mode in which sample gas flows into and out of the dehydration unit through a first port and a second port, respectively, wherein the volatile organic compounds in the sample gas are concentrated in the concentration unit. The temperature control unit may be configured such that the temperature of the sample gas after flowing out from the dehydration unit and before flowing into the concentration unit is not greater than a first preset temperature. Generation of condensed substances in the sample gas can be effectively avoided in a simple manner after the sample gas flows into the concentration unit, thereby further preventing ice blockage. Methods for detecting volatile organic compounds in a sample gas are also disclosed.