Abstract: Using long-term observed phenological data, research on the trends of crop phenology is a vital approach to understand the impact of climate warming on agricultural production. In this study, the trends in wheat and maize for 1981 to 2009 were investigated based on phenological data from 13 agro-experimental stations in Inner Mongolia by using statistical methods. The study showed that the response of wheat and maize phenology to climate change was different under the combined effect of management change (sowing date adjustment) and cultivar shift. Across the investigated stations, while sowing date of wheat was delayed on an average of 1.7 d/10 a, maize sowing date was in advance with an average of 1.0 d/10 a. The heading date and the subsequent maturity date of wheat were delayed on an average of 1.7 d/10 a and 0.8 d/10 a. Although heading date of maize showed small changes, the maize maturity date was delayed on an average by up to 3.3 d/10 a. Furthermore, trends in duration of different growth stages for wheat and maize were significantly different. The duration from emergence to heading (VGP) of wheat was shortened by an average of 1.4 d/10 a, while VGP of maize was prolonged on an average of 1.2 d/10 a. Also the durations from heading to maturity (RGP) of wheat and maize were prolonged on an average of 0.2 d/10 a and 3.3 d/10 a, respectively. However, the duration from emergence to maturity (WGP) of wheat was shortened by an average of 1.2 d/10 a, while that of maize was prolonged on an average of 4.5 d/10 a.