The design of a frequency reconfigurable waveguide slot antenna using silicon-based plasma is presented in this paper. Firstly, the lateral PIN diode is introduced, and a double lateral PIN diode structure based on the lateral PIN diode is proposed. The operating principle of the double lateral PIN diode is also presented. Secondly, combining the waveguide slot antenna and the double lateral PIN diode, a new type of frequency reconfigurable waveguide slot antenna is put forward. At last, the modeling and simulation of the proposed antenna are completed. The simulation results indicated that the frequency reconfiguration of the antenna has been realized at 103.5, 104 and 104.5 GHz.