We conducted a study on the population dynamic of the two major aphid species of green peach aphid, Myzus persicae(Sulzer), and cotton aphid, Aphis gossypii (Glover), as well as their natural enemies on the five major green house crops in Chinju greenhouse vegetable area in Korea. The green peach aphid was relatively the majority among all aphids collected from tomato, potato, and chinese cabbage, while the cotton aphid was major species on water melon and hot pepper. Both species reached their peaks in mid June, when the summer monsoon was not initiated, the temperature was relatively as low as 23$^{circ}C$, and the crops were young and favorable. the density of predators such as spiders, lady beetles and green lacewings and some other arthropods were very low in the early season and reached their pick three weeks after the aphids density peaked. This data indicated that the predators only follow aphid abundance but arrive too late to be effective as regulators of aphids population. About 9,255 samples of various aphids collected from the five crops, we found 39 parasitoids representing at least eight different species. Aphidiid sp. occupied 35.8% and hyperparasites occupied 56.5%. Lipolexis scutellaris species was ver scarce and only occupied 2.6% from Aphis gossypii on watermelons. This information can be used for determining the impact of natural enemies under the mixture of greenhouse-open field vegetable production system.