The topic of the final paper is the research of the influence of the mold channel for polymer injection molding on the mold parameters (filling time, pressure...). Since the trend in the production of molds is the use of additive technologies, especially polymer molds, special emphasis in the work is placed on the distribution channels. With additive technology there is the possibility of making different cross-sections of the channel. The first chapter briefly explains what injection molding is, its history, parts of the mold are briefly explained and what are the procedures to achieve one whole cycle. The second chapter explains the making of molds using additive technology. It is briefly explained what additive production itself is and some of the additive technologies used to make molds are listed. In the third chapter, significant parameters for polymer injection molding, for example the construction of the mold itself, are discussed. Two parts have been constructed to be simulated in the Moldex 3D software package. Several types of different cross-sections of the inflow channel were constructed. In the fourth chapter, a simulation of polymer injection molding through three different inflow channel designs is made and their comparison with theoretical values.