Abstract: The paper aims to quantify the temperature effect on phenological development of winter maize planted in tropic region, and build a new phenological model with better explanation. Field experiments were conducted with different maturity cultivars and sowing dates in three sites in Yunnan tropical region(Ruili, Longchuan, and Mangshi County) for three years, to compare the accuracy of different predicted methods. With 0℃, 6℃, 8℃ and 10℃ as lower bound, four accumulated temperature models did not predict accurately with RMSEs from 7 days to 11 days. A new maize development model was developed based on WOFOST, in which the daily maximum temperature and daily minimum temperature took place of the daily average temperature, and a piecewise function was set with particular base temperature for each phenophase. This new model was validated by independent experiment data. The RMSEs of this model was 4.42 d and 4.19 d for two cultivars respectively. This new model showed higher accuracy and was more explanatory. It could explain the effect of temperature variation within-day and the difference of different phenophases.