Abstract: Patulin is a neurotoxic secondary metabolite that causes a series of acute and chronic conditions such as enteritis, dyspnea and cancer when the body consumes excessive amounts. China is the birthplace of kiwifruit and the largest producer of kiwifruit in the world. A large number of studies had shown that kiwifruit is susceptible to infection with penicillium expansum (P.expansum) and patulin accumulation during harvesting, storage and processing which not only causes waste, but also harms human health. Therefore, it is necessary to study a safe and effective method to control P.expansum and patulin accumulation of kiwifruit and its products. Trans-2-hexenal is a characteristic aroma component naturally present in kiwi, apple and other fruits. Studies had shown that trans-2-hexenal has a certain inhibitory effect on microorganisms. This article studied the inhibitory effect of hexenal on the growth of P.expansum and the production of patulin. Firstly, the five strains of P.expansum (CICC40658, CGMCC3.3703, LPH6, LPH5, WY) were inoculated into PDA medium plates containing bacteriostatic substance concentration of 5 mg/mL which kept at 28 ℃and the diameter of the colony was measured by the cross method every day. Study the antibacterial effect of trans-2-hexenal and eight antibacterial substances reported in the literature (citric acid, limonene, malic acid, γ-aminobutyric acid, quercetin, catechin, sodium diacetate, oxalic acid) on 5 strains of P.expansum. Determined the minimum inhibitory concentration of trans-2-hexenal by antibacterial test of 5 strains of P.expansum when trans-2-hexenal at a concentration of 40, 60, 80, 100 μL/L. Then 3 mm of sterile iron nails were used to perforate the equator of kiwifruit and 10 μL 1.0×106 cfu/mL spore suspension of 5 test strains were inoculated which simulating injury of kiwifruit secondary infection P.expansum. The kiwifruit in vivo test was carried out by adding trans-hexenal aldehyde at a concentration of 100 μL/L and determined the kiwifruit hardness, soluble solids, titratable acid, reducing sugar, vitamin C, pH value and fruit decay rate to study the effect of trans-2-hexenal on the quality of kiwifruit and the patulin content in kiwifruit was measured by HPLC. Lastly, the effect of trans-2-hexenal on the morphology of 5 strains of P.expansum was observed by scanning electron microscope. The results shown: Compared with the eight antibacterial substances, trans-2-hexenal had the best antibacterial effect and it could completely inhibit the growth of 5 strains of Penicillium expansum. The minimum inhibitory concentration (MIC) of the five strains was 100, 80, 80, 80 and 80 μL/L, respectively; trans-2-hexenal significantly reduced the effect of P. expansum on kiwi fruit firmness, titratable acid and vitamin C (P<0.01)and had no significant effect (P>0.01) on the fruit firm, soluble solids, pH value and reducing sugar content of kiwifruit. The rot rate of kiwi fruit with P. expansum was reduced and the quality of kiwifruit was better maintained by Trans-2-hexenal. All the aldehyde-treated kiwifruits were not detected by patulin; the scanning electron microscope showed that the five strains showed hyphal shrinkage, folding, drying, and sporulation reduction. Trans-2-hexenal has a good inhibitory effect on the growth of P.expansum and the production of patulin and provides a theoretical basis for the development of natural products with antibacterial effects.