Abstract: In order to determine the most suitable planting site and crop variety, an ecological experiment was conducted on the effect of elevation on maize growth during 2006 ~ 2007. The study utilized seven maize varieties in five experimental stations across Gansu Province, and five maize varieties in five experimental stations across Yunnan Province. The results show that at the same sowing time, jointing stage, heading stage and maturity stage of maize prolong with increasing elevation. In other words, the durations from sowing to jointing, jointing to heading and heading to maturity become longer with higher elevation. Growth period is therefore positively related with elevation at 0.01 significant level. But when elevation rises 100 m, maize growth becomes sluggish by 4 ~ 5 days. Maize plant height and ear leaf number reduce with rise in elevation.