As an important physical phenomenon caused by thermionic emission, the virtual cathode not only has significant scientific research value, but also has broad application prospects. In our recent research, a one-dimensional model of thermionic emission was established, and the analytical expressions for the potential barrier and the spatial width of virtual cathodes were derived, which were of great significance for improving the understanding of virtual cathodes and developing methods to control the virtual cathode characteristics. In this study, based on the existing theoretical, we further establish a control theory of virtual cathodes and develop a complete virtual cathode control system accordingly. The hardware components of this control system mainly include a vacuum chamber, a hot-cathode filament, an anode, a capture card, a computer, a cathode heating circuit, a cathode scanning bias circuit, and an infrared temperature measurement system, etc. Using the control system, it is possible to achieve accurate control of the virtual cathode potential and width in a vacuum by adjusting parameters such as the cathode heating temperature and the electron collection current. Taking a tungsten filament as the research object, the virtual cathode potential and width generated by the tungsten cathode were measured and controlled respectively by using the method of controlling variables. The experimental results show that the virtual cathode potential increases linearly with the rising heating temperature when the ratio of electron collection current to saturated electron emission current is kept constant, and decreases logarithmically with the increase of the electron collection current when the heating temperature remains constant. On the other hand, when the strong virtual cathode condition is met, the virtual cathode width is proportional to the three-fourths power of the heating temperature, inversely proportional to the square root of the electron collection current, and is independent of the cathode material parameters.