The biology of corn aphid, Rhopalosiphum maidis (Fitch) was studied at Plant Protection Research Institute in 2014 under laboratory conditions (26.4 +/- 0.15oC and 78.0 +/- 1.25 percent RH), using hybrid corn cultivar (hybrid sticky corn AG500) and local corn cultivar (ngo te ban rang ngua) as food. Obtained results showed that nymphs went through four instars. The duration of the first instar, second instar, third instar and fourth instar of nymphs and pre-reproductive period lasted 1.52-1.76, 1.52-1.76, 1.45-1.68, 1.45-1.68 and 0.75-1.05 days, respectively. The corn aphid completed its life cycle from 6.60 days on hybrid corn cultivar and to 7.93 days on local corn cultivar. The reproductive period lasted from 10.5 days on local corn cultivar to 12.5 days on hybrid corn cultivar. Each corn aphid adult laid an average of 28.6 nymphs feeding on local corn cultivar and 35.9 nymphs feeding on hybrid corn cultivar. The longevity of the adults was about from 11-12 days on local corn cultivar to 13-14 days on hybrid corn cultivar.