Impacts of climate change on agriculture has received wide concerns, yet evaluation technology of the effect of the drought disaster on the crop yields needs further research particularly in developing countries. Maize cultivation occupies extremely important position in agricultural production in this region. It holds great importance to study the evolution of the drought to provide references for disaster prevention and avoiding disadvantages. Drought is the main meteorological disasters during maize growth periods, and high frequency and large-scale drought poses serious threat to maize growth and yield. Recently, the government departments and related research institutions have focused on the drought matter in Southwest. Based on the principle of similar climate growth period and agricultural production level, corn planting areas in Southwest China are divided into 6 sub-regions. Using the daily meteorological data and maize data from 63 representative stations in Southwest China from 1961 to 2010, the study calculated water profit and loss index in each sub-region, then computed the weighted sum of the water profit and loss index over the past three ten-day, finally got the ten-day wetness index. According to the ten-day wetness index and influence coefficient, the maize cumulative index was built. The study developed yield drought loss assessment model and verified the model by selecting some typical drought years and representative stations in each sub-region. The results showed that the wetness index by 10 days in the growth period had a good relationship with soil moisture. The assessment model of maize drought loss yield in 6 sub-regions passed F-test (p<0.05) and corn cumulative indices of drought in drought year in Southwest China had good relation to the yield loss in drought through the statistical analysis of the representative station. With changes of the same drought cumulative indices, there were slight differences in yield loss in each sub-region. Yield loss in the sub-regions ofⅡandⅢwere relatively small, while relatively large in the sub-regions ofⅠandⅤ. The model can estimate the yield loss in drought accurately, and provide references for application and deep research.%为研究干旱对西南地区玉米产量的影响，该文根据气候相似、发育期相近、农业生产水平相当的原则将西南地区玉米种植区分成6个亚区，利用1961－2010年西南地区63个代表站点逐日气象资料，计算逐旬水分盈亏指数，建立逐旬干湿指数，并基于旬干湿指数建立玉米干旱累积指数，同时结合玉米单产资料，构建玉米干旱产量损失评估模型。结果表明，玉米生育期内旬干湿指数与该旬的土壤湿度相关性较好；西南6个亚区玉米干旱产量损失评估模型均通过0.05水平的F检验，通过代表站、西南干旱年玉米干旱累积指数与干旱产量损失间的统计分析，两者之间具有显著的相关性，检验水平F均在0.05以上。模型能较准确地评估玉米发生干旱时的产量损失，具有一定的应用和深入研究价值。
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