We describe the construction of a 3D seismic velocity model that may serve as a reference for geophysical investigaions in eastern Taiwan, where the westernmost Ryukyu subduction zone connects to the active arc-continent collision zone. For offshore region where local tomography is not available, we construct the model by intergrating multiple geophysical data sources in order to characterize, in geometry as well as in velocity, the different structures existing in the area. The multiple data sources used to creat the offshore model mainly consist of seismic reflection and refraction data to identify crustal structures and a global hypocenter dataset to define the subduction distinguished in this work include the water layer, sedimentary units (e.g., forearc basins and accretionary prism), the oceanic crustal basement of the Philippine Sea plate, the thickened crust of the Luzon Arc, the subducted Philippine Sea slab, and the curved Ryukyu margin. This investigation results in the first comprehensive Vp velocity model for the region and covers the area from 121.0 – 124.4°E and 22.0 – 25.3°N, with its depth reaching 120km.