A heart-cut two-dimensional GC/MS instrument consisting of a GC and a GC/MS was fabricated based on pneumatic pressure controlled switch (i.e. Deans switch). The instrument included dual ovens for two columns and a cold trap cooled by liquid nitrogen between two columns. It was easy to construct and operate. A method for analysis of nitroalkanes in cigarette mainstream smoke was developed with the instrument. The gas phase compounds of cigarette mainstream smoke were directly analysis without cleanup after trapping by ethyl acetate under -70°C. Multiple cuts were executed in one injection, and the cuts were trapped on the head of the 2nd column through transfer line between two GCs. Nitromethane, nitroethane, 2-nitropropane and 1-nitro-n-pentane was detected and quantified from the cigarette mainstream smoke. The limits of detection for nitroalkanes ranged from 1.30 to 9.80ng/cig. The recoveries ranged from 87.1 to 110%, and the RSD was between 7.17~9.43%.