The main topic of this paper is the optimization of the die casting process. In order to be able to present ways of optimizing the die casting process, first it is necessary to show the structure of die casting cell, which is used for production of high-pressure castings. The main part of die casting cell is the high-pressure casting machine, which is surrounded by periphery without which the production of casting would not be possible. For this reason, the periphery which is located in die casting cell, and what function each element has, will be described first. In order to be able to optimize the casting process, it is necessary to know in detail each of the peripheries and their impact on the process. Without knowledge of the periphery, optimization is not possible. Furthermore, the main errors that can occur in high pressure castings are described. In this part it is explained how a particular error occurs, and what are the possible causes. In practice, it is usually not possible to know immediately what the main cause of defect is, but it is necessary to go in order and check all possible causes. In order to make defect solving easier, a table of defects and possible causes was made. Also, the optimization of high-pressure casting cannot be performed if it is not known how the error occurs and what the possible causes are. The last part will be based on the optimization of the die casting process. As mentioned, optimization most often refers to resolving individual defects that cause poor piece quality, and high amount of scrap. But optimization also means reducing the casting cycle, reducing energy consumption, increasing the degree of automation, increasing tool life, and so on. In the final part, examples of optimization of high pressure die casting from practice will be presented.