Abstract: To investigate the effect of the frying treatments on the chemical composition of piper essential oil in the fresh pepper, the different material oil ratio, the different oil temperature and the different frying time were studied. The piper essential oil had 18 kinds of chemical compositions in untreated fresh pepper. The piper essential oil had 28, 23, 28, 25 and 26 kinds of chemical compositions respectively, when the oil ratio were 1:1, 1:1.5, 1:12, 1:2.5 and 1:3. While the frying temperature were 90°C、100°C、110°C、120°C and 130°C, the kinds of chemical compositions in piper essential oil were 21、26、23、27 and 23. Meanwhile the piper essential oil respectively had 29、22、23、22 and 26 kinds of chemical compositions fried for 1 min, 2 min, 3 min, min 4, and 5 min. The results showed that the different frying treatments could increase the chemical compositions of piper essential oil. The main chemical compositions were Caryophyllene, 3-carene, D-limonene, L-β-pinene, α-Phellandrene and α-pinene.