Previous studies indicate that some slow-mode magnetoacoustic waves observed in solar coronal loops originate from the sunspot photosphere. However, the derivation of the detailed travel paths and speeds of the waves, as a function of atmospheric height, is complicated by the lack of three-dimensional structure of the coronal loops due to the projection effect, as well as the wide ranges of spectrum formation heights of the UV/EUV channels used in the observations. In this study, by applying a DEM method on SDO/AIA multi-channel observations in EUV, we construct the EM maps of a coronal loop at different temperatures. Tracking the rotation of the Sun, we are able to construct such temperature-dependent EM maps when the coronal loop is at different disk locations. Then, at each different temperature and at each disk location, through cross-correlating oscillation signals we map the magnetoacoustic waves’ projected traveling paths. Assuming the coronal loop is stable, and the property of the waves does not change much with its viewing angle, we are able to set up a series of linearized equations depicting the waves’ traveling at different temperatures. Solving these equations gives us the detailed traveling paths and speeds of the waves at different plasma temperatures.