Abstract: The paper aims to breed new cucumber varieties with high resistance to aphids, and provide theoretical basis for the identification of cucumber aphid-resistance. According to the method of ratio of aphid, the hairy cucumber (an ordinary cucumber) was used as the control of less anti- aphid ability, while the glabrous cucumber (the mutant of the ordinary cucumber, its surface is smooth without hairs, with high anti-aphid ability) was used as the control of anti-aphid, 370 home and abroad cucumber germplasm resources were taken as test materials to the anti- aphid screening classification, and aphids were inoculated to the cucumber materials with different levels of anti-aphid ability. The author studied the content change of some secondary metabolites including flavonoids, tannins and total phenol, and the enzyme activities of phenylalnine ammonialyase (PAL) and polyphenol oxidase (PPO) in the leaves before and after inoculation of aphids. The results showed that: the anti-aphid material was No.118, the medium anti-aphid materials were No.311 and No.227, and the low anti- aphid material was No.321. After inoculating aphids in leaves, the content of flavonoids and the activity of PAL and PPO in the leaves of the glabrous cucumber, which was the high antiaphid material, were higher than that of the other anti-aphid materials; the contents of tannins and total phenol in the leaves of No.118, which was the anti-aphid material, were the highest among the anti-aphid materials, and the activity of PPO in its leaves was second only to that of the glabrous cucumber; the content of tannins and total phenol, as well as the activity of PPO in the leaves of the medium anti-aphid material No.227 were second only to that of No.118; the content of flavonoids and total phenol, as well as the activity of PAL in the leaves of the medium anti-aphid material No.311 were higher; the activity of PAL in the leaves of the low antiaphid material No.227 was second only to that of glabrous cucumber; the content of flavonoids, as well as the activity of PAL and PPO in the leaves of the anti- aphid materials were all higher than that of the hairy cucumber. In conclusion, by this test, cucumber materials with different levels of anti-aphid were screened, and aphid-resistance of different cucumber materials had a close relationship with the contents of flavonoid, tannin and total phenol which were secondary metabolites, as well as the PAL and PPO which were the most important enzymes in the secondary metabolic processes.