Abstract: Abstract: As one of the important factors affecting crop growth, agricultural heat resources directly determine the local crop type, variety distribution, farming mode, and farming activities. The objectives of this study were to clarify the changing rule of spring maize climate resources in Inner Mongolia, to quantify the impact of climate change on spring maize water requirements and yield, and to promote the optimal allocation of water resources and food security in the region. Based on the data from 113 meteorological stations in Inner Mongolia, crop growth period data, and statistical crop coefficient values, the study analyzed the spatial changes of accumulated temperature (≥10℃) and spring maize cultivation mode (early, middle early, middle, middle late and late maturity) under 80% assurance rate using the five-day moving average method. The planting boundary and variety maturity change of different maturity spring maize under the background of climate change were explored, and on this basis, the impacts of climate change on effective precipitation, crop water requirements, and irrigation water requirements during the growth period were quantified. Finally, the changing trend of the main meteorological factors during the growth period of spring maize was analyzed, and the correlation between the main meteorological factors and the yield of spring maize was established using a stepwise regression model. The results showed that: 1) From 1959 to 2018, the accumulated temperature in Inner Mongolia increased. The accumulated temperature from 2009 to 2018 increased by 263℃ compared to that from 1959 to 1968, and the accumulated temperature contour shifted significantly. The boundary line of different maturity types of spring maize moved northward and expanded eastward obviously, and the change of maturity types in the central and eastern regions was the largest. Spring maize changed from unsuitable planting areas to early and medium maturity types. The early maturing area expanded to the northeast, and the area suitable for spring maize planting had an increasing trend, while the unsuitable planting area was finally retained in the northern part of Hulun Buir. Among them, late-maturing maize varieties occupied the largest area. 2) The effective precipitation during the growing period of spring maize from 1959 to 2018 was 114 mm, and the spatial distribution showed an increasing trend from west to east. The high-value area was mainly distributed in Zhalantun of Hulun Buir, while the low-value area mainly occurred in Guaizihu and Ejin Banner of Alxa League. The spatial distribution of crop water requirements was opposite to the effective precipitation, and the overall distribution trend was decreasing from west to east. The high-value area was mainly distributed in the western Alxa League, while the low-value area was mainly distributed in Ulanqab. The coupling degree between crop water requirements and effective precipitation and groundwater recharge was between 0.02 and 0.40. In terms of spatial distribution, the high-value area was mainly located in the middle east and the northeast, and the low-value area was mainly located in the Alashan League. The reduction of effective precipitation and the increase in crop water requirements promoted the overall downward trend of the coupling degree in this area. 3) Among the meteorological factors, the temperature showed an upward trend, and the other factors mainly showed a downward trend. Stepwise regression analysis showed that precipitation was the main factor affecting the yield of spring maize in this area. This study can provide valuable information for the spatial distribution of spring maize and the efficient utilization of water resources in Inner Mongolia.