Mudflat is the primary foraging habitat of wintering shorebirds. Shorebird distribution is related to substrate of mudflat. The wintering population of Eurasian Curlew (N. arquata) shifted its distribution in the past 30 years in Chang-hua coastline. To understand the cause of the distribution change, we need to know which mudflat types preferred by curlews. We used Landsat image to classify substrate to mud and sand by supervised and unsupervised classification. 138 sediment samples were collected for verification. Overall accuracy of supervised and unsupervised classification is 94% and 92%. We observed curlews’ distribution and behavior in the field and digitized distribution range on the classified image. We found that curlews distributed on muddy mudflat for resting and foraging, where is closer to the roosting sites. Muddy mudflat might provide curlews (1) higher prey availabilities, (2) suitable condition for bill’s shape, (3) food supply. To study the change of distribution of shorebirds on intertidal zone might need to consider the food source and the distance of high-tide roosting site. We present the first study of the habitat use of N. arquata in the East Asian-Australasian Flyway by satellite image.