Abstract: The study aims to avoid site interpolation error and achieve convenient and efficient application of CLDAS data with high precision and spatial distribution to the climate suitability index of regionalization. Based on dynamic suitability calculation method of Inner Mongolia corn, GIS’Model Builder was used to construct automated calculation model of daily temperature suitability of corn, which had the functions of extracting CLDAS hours data, calculating daily average temperature, calculating the optimal temperature, lower limit temperature and maximum temperature, constructing piecewise function and error analysis. CLDAS data on May 25, 2016 was used to analyze the operation efficiency of daily space temperature suitability calculation model. The results showed that: the mean absolute error of average temperature of CLDAS and site observation value was 0.57℃; the mean absolute error of temperature suitability index of CLDAS and site observed suitability was 0.02 and the average relative error was 3.17%, which indicated high fitting precision; daily temperature suitability index calculation model had achieved suitability index of routing computation with simple operation and convenient popularization, which had high practicability and fulfilled the application of CLDAS in climate suitability index of regionalization.