Two independent columns containing different stationary phases are connected in series by a modulator in Comprehensive 2D GC (GC×GC). Each component from the first column is focused by the modulator, and then the sample is pulsely injected to the second column for continuous separation, so as to realize the orthogonal separation of components with different boiling points and different polar components. Compared with the conventional 1D (single column) GC, GC × GC has the characteristics of large peak capacity, high resolution, high sensitivity and family separation. It has a strong advantage in the complete component analysis of complex samples and rapid analysis of simple samples.