There is presented application of Graph Data Base technology in knowledge engineering task concerned with knowledge representation of complex structures. The first example is graph representation of composition of tractor gearbox. It is an example of application of static partonomy relation. Adequate codding of that relation in Graph Data Base is easily expressed in Cypher language. There were presented some applications of Graph Data Base useful in management of technical object existence in different “life” phases, as design, production, maintenance and recycling. The second example concerns the Graph representation of activity structure. Such structures was built based on agricultural tractor’s technical revisions system. Created Data Base allows for processing the queries referred to the questions of what activities in what period should be performed to maintain the agricultural tractor ready to work in good technical condition. The Graph Data Base technology is the first step to create semantic systems for data storing and processing in order to extract knowledge and information useful in precise physical process management.