Hexanal is one of the most important aroma compounds which play a crucial role in the odor of cereal, meat, fruit, plant oils and wood. The detection technique of hexanal has attracted more attention. In this paper, the nano-SnO2 flat-type coplanar hexanal gas-sensor arrays were fabricated by screen-printing technique based on nano-SnO2 powders prepared by hydrothermal method. The test results show that the nano-SnO2 flat-type coplanar gas sensor arrays have good hexanal gas-sensing characteristics, such as low detection limit and high sensitivity. Especially, the gas sensitivity of the nano-SnO2 gas sensor arrays to 100 ppb hexanal can reach 2.8 at 350 degrees C. The nanometer size effect of nano-SnO2 and nature property of hexanal caused the ppb-level hexanal gas sensing characteristics.