The paper describes the main features of the specialized input language of the computer-aided system for shaft press forging processes. The system has been developed at the Institute of Engineering Science, Ural Branch of the Russian Academy of Sciences. The developed input language allows users to make adjustments in an implementation forging sheet, starting from the selection of an ingot to the design of preparatory and main forging transitions. Each adjustment is a choice of the required solution in a drop-down menu, for example, the choice of the required ingot from the list of suitable ones, or a binary decision (forging or not forging an axle, including or excluding the selected ingot upset). Ot it might be changing numerical values of process parameters, which are within certain limits (intermediate blanks sizes, forging ratio, etc.). Since the boundaries of technological limitations are fuzzy due to the lack of formalization of the subject area in general, i.e. they are within a certain range of their values; the input language provides users with the opportunity to make adjustments to the system solutions with “insignificant output” beyond these boundaries. The computer-aided design of forging technological process has the determined technological rules taken out to the system knowledge base. A constituent part of the input language, which is related to the system knowledge base, allows efficient adjusting the technological design rules, which can be different in various enterprises, without modifying algorithms and programs. Application of the input language guarantees obtaining implementation forging sheets suitable for using in a production process and facilitates system implementation in various companies.