In order to estimate the position of the unmanned aerial vehicle (UAV) in an indoor disaster environment, it is recommended to utilize methods using wireless signals regardless of smoke or dust. Among the wireless signal-based localization methods, UWB-based localization is becoming more popular. In an environment surrounded by walls or pillars, there is a significant difference between UWB signal's line-of-sight (LOS) measurement and non-line-of-sight (NLOS) measurement. In this paper, we propose the UWB-based localization method that compensates for UWB ranging measurement by predicting NLOS multipath using a ray-tracing algorithm based on given floor plan. Experiments were conducted indoors in the test complex site. The experimental results verifies that the proposed algorithm has improved localization performance compared to the traditional algorithms.