The article analyzes and formulates pre-requisites of creation, conceptual framework and main functions of new GPSS Studio simulation environment for research of complex discrete-event systems. GPSS World simulation language is used as a simulation environment kernel. A number of new notions were introduced during the creation of simulation environment: shared research space, a simulation project, model dynamic monitoring, a simulation application and a virtual report. The article shows features of integrated application of simulation environment at all simulation phases with the use of model hierarchy diagrams, a text editor, automatic model code generation, a model debugger, an interactive standard simulation report, model source and simulation results databases, online analytical processing means of model measures change dynamics, conducting an optimization experiment. The main environment tools for creating simple and available for mass user simulation applications are described with due regard to the aspects of the domain of the system under study.