In this work the method of computer simulation of microwave devices is considered and the special virtual laboratory workshops are created. The simulated laboratory has module structure. At the model basis the concept of the abstract "device" which configuration in installation is identical to real devices underlies. As an example the laboratory work is simulated with the set of the following devices: swept frequency generator, the VSWR/attenuation scope and the studied device which is a waveguide slot antenna. In the virtual laboratory program interface the user can change the frequency markers, the dimensions and displacement of slots to carry out all necessary measurements of antenna internal characteristics, thus the frequency characteristic of the studied device is displayed on the screen of the indicator unit in real time.