Unmanned transport aircrafts (UTAs) are emerging airborne platforms for rapid arrival and low-cost transport. The landing limit weight of UAVs, as an important constraint on capacity and endurance, is an important consideration in programme design, airworthiness certification and customer operations. Its field adaptability affects the accessibility of logistics services and frontline security delivery. This paper analyses and calculates the factors affecting the landing weight limitation of fixed-wing UAVs based on the analysis of relevant airworthiness standards and weight limitation requirements. This paper mainly analyses the landing speed setting and climb optimization design. The methodology of this paper can be used for fixed-wing unmanned transport aircraft programme design and evaluation, and provides certain guidance and reference value for practical use.