The paper considers the problems of computer simulation of modern lighting devices (LD) based on light emitting diodes (LED) and their optical systems (OS). LED OS provides developers with sufficient opportunities to implement a variety of problems of modern lighting. In the market of competing products, it is often necessary to calculate and manufacture LED optics for specific lighting problems, the main of which is the formation of a given distribution of illuminance over the surface of an object. It is shown that the most demanded services in LED lighting engineering are the development of LED optics according to the customer’s specifications, lighting engineering testing of a modelled product, development of 3D models for further production. The main stage in the context of such design is the calculation and simulation of the OS. The results of this process are basically determined by the complex of luminous, thermal, and functional characteristics of LD. The development of modern LED LD is inseparably linked with the use of specialized software. Modern technologies and approaches, CASE-tools in the design of the LD, the main requirements for the LD models, integrated complex AllFusion Modelling Suite are considered. Functional diagrams of the process of designing the LD have been developed. 3D models of single and block lenses and reflectors of various designs have been developed in the computer-aided design system KOMPAS‑3D. For given LED properties, selected materials, and ray tracing conditions the light distribution of LED modules was obtained and analysed in TracePro software. Acceptable results have been obtained, that is why this approach can be recommended for prototyping and studying the characteristics of experimental samples of LED modules and LD.