Within production system designing are important especially these activities: philosophic and conceptual aspects of technological innovation, modelling, existing solutions certified in praxis, financial and material security of innovation changes and multi-purpose and purpose innovation projects. The aim of every project is optimal reduction of designing processes by simultaneous observance of required quality and costs minimisation. Nevertheless it is important to use innovation methods, tools and procedures within solving the various designing problems. This article is oriented on the designing of assembly system through the interconnection of virtual reality and physical reality. The result of this connection is mixed reality, which can be used as a useful tool in the 21st century.