With the help of functionalities of packages of computer design Unigraphics and PRO/ENGINEER the finite-element model of a skeleton of a cabin of a tractor "Belarus", used is generated at carrying out of natural experiments on proving grounds of a factory. Import of the obtained discrete model finite-element package ANSYS is executed and calculation of a spectrum of frequencies of free vibrations of a cabin is carried out in view of the boundary conditions corresponding to a case when the skeleton is rigidly fixed on four arms of a frame of a tractor. The main forms corre-sponding to first twenty own frequencies, and also shown moving of elements of a skeleton for these main forms of vibrations are constructed.