The invention relates to a two-dimensional back flush gas chromatograph gas circuit and an analysis method thereof, and belongs to the technical field of gas chromatography in order to solve the problems of long analysis time and low detection ability of traditional analysis methods of an aniline and water blend system mixture in a diaminodiphenylmethane product. The gas circuit adopts a thermal conduction cell back flush system as a primary chromatograph and a hydrogen flame back flush system as a secondary chromatograph in order to obtain a two-dimensional back flush chromatograph. The analysis method realizes simultaneous analysis of tiny amounts of water and aniline in the diaminodiphenylmethane product through switching the connection state of a six-way valve 1 and a six-way valve 2. The gas circuit adopts a gas phase back flush technology in order to back flush impurities, so the analysis time is saved, and the sample size is increased in the same time, thereby the detection ability is improved. The gas circuit and the method are used for gas chromatography.