云检测是卫星资料应用的基础,其结果直接影响相关定量反演的精度。通过对21.0°N~27.0°N，117.0°E~123.0°E范围的MODIS数据进行数字滤波，根据遥感原理统计得到目标区域云、水体、平原、山地等不同下垫面辐射特性，将其与多通道阈值法相结合，依据统计结果选定通道1、6、31、32数据为云检测特征量并设定相应阈值。检测实验表明其对厚云的检测效果较好，但对薄云、卷云检测能力有限。依据大气辐射传输特性，以通道26数据和分裂窗通道差值为特征量检测卷云、薄云以作为补充，得到理想的检测效果。将检测结果与MODIS云检测业务算法得到结果对比分析表明，本文方法在目标区域的云检测更为精确。

As cloud can significantly affect image qualities in the earth studies,cloud detection plays an important role in analyzing satellite images.Much work has been done on it all over the world,these methods are suitable for large area,but sometimes the precision can’t meet the requirement.Based on the theory of remote sensing and digital filtering，We conduct statistical analysis on a local area (21.0°N~27.0°N,117.0°E~123.0°E).Through the statistic,characteristics and thresholds that are useful for the target area are found,which are Ref1,Ref6 and BT31.As a supplement,it selects Ref_26Land and BT31-BT32>Th31-32 to detect cirrus and thin cloud. At the end,the result is analyzed by comparing it with the outcome of MODIS operation arithmetic,which found this method improves the precision of cloud detection.