The goal of this graduate thesis is to optimize the composite structure of the unmanned aerial vehicle, that is, the composite layup in the composite material. In the thesis, a numerical model of the aircraft was created for analysis using the finite element method in the program Abaqus/Standard 2021. After that, critical load case was determined. The calculation was carried out using available failure criteria for composite materials and those are Hashin, Tsai-Wu and Tsai-Hill yield criteria. The work explains the criteria and reasons for their use. In the Isight 2021 program, using built-in optimization techniques, multiple optimization processes were conducted for two different versions of the aircraft that used two different materials. An optimization model was defined in the Isight program, which enables multi-criteria optimization of the numerical model. The aim of the optimization was to reduce the mass of the aircraft while maintaining the desired strength and stiffness, through the process of several separate optimizations the number and orientation of the plies, the type of composite material and the thickness of the core of the sandwich structure were varied. In addition, an analysis and comparison of different optimization techniques available in Isight was performed and the best one was proposed for this type of optimization problem. The optimization results showed a reduction in the weight of the aircraft and the possibility of achieving exceptional rigidity. Also, the thesis describes a simplified construction and gives critical comments on the obtained results. At the end of the work, the next steps for further research are suggested.