Advancement in UAV technology has led to its more widespread role. An emphasis on fuel efficiency and operational range has become a standard operational requirement for UAV designs. As these requirements become more stringent, better structural designs that reduce the weight of UAVs have become increasingly important. However, these structures are often of complicated design which requires advanced manufacturing methods. One such method is additive manufacturing (AM) that is capable of fabricating complex parts with high precision and strength. This manufacturing method is suitable for structure such as IsoTruss which has complex geometries. In this paper, we perform numerical analysis using finite element method on IsoTruss structure and standard I-Beam structure as UAV wing spar. The aim of this analysis is to determine the IsoTruss performance as a viable option for a small UAV wing spar. From the analysis performed, using IsoTruss reduced the weight of the structure by 21.78%. This reduction in weight could be useful for UAV designs that require long duration of flight and wide operational range.