The software package "MVTU" (Modeling in Technical Devices; in Russian - Modelirovanie V Tehnicheskih Ustrojstvah) is intended for research and design of the systems described by the differential, algebraic and difference equations. Complex technical object is a controlled object, therefore in the package "MVTU", along with the methods of simulation, the methods of control theory are implemented. In terms of features this package is an alternative of package Simulink, which is a part of system of mathematical computations MATLAB. As well as in the package Simulink, in the package "MVTU" representation of mathematical model in the form of block diagram is accepted. Blocks of such diagram are described by the differential and difference equations, continuous and discrete transfer functions, algebraic relations and logical conditions. The package "MVTU" implements the following operating modes. The operating mode Simulation provides simulation of continuous, discrete and hybrid systems, including in real time in the presence of data exchange with external programs and devices. The mode Optimization allows us to find optimum parameters of the designed system. The modes Analysis and Synthesis provide the solution of problems of research and design of control systems with use of frequency and root methods. The paper describes the main features of the package "MVTU" according to the solution of problems of the analysis, synthesis, simulation and parametric optimization of automatic control systems. Examples of the solution of such problems are given. Experience of the solution of a large number of educational, scientific and applied problems showed that the package MVTU doesn't concede by the opportunities to the best foreign analogs.