In order to improve the stability and reliability of the traveling wave tube (TWT), the optimization and design of the electron beam have become a key part in vacuum electronic devices. Laminar properties are a key parameter for evaluating the quality of the electron beam. The transverse displacement of the particles in the laminar electron beam is proportional to the transverse velocity. In the phase space distribution image of nonlaminar properties electrons at a certain position, there is no linear relationship between the transverse displacement and the transverse velocity. Since the energies of each particle in the electron beam are different, this leads to different initial velocities of each particle. The particle source at the electron beam waist in the electron gun is adopted as the particle source for the beam wave interaction simulation. The output characteristics of the TWT are closer to the actual situation. A method of simplifying the particles at the electron gun beam waist into macroparticles using the K-means clustering algorithm is proposed. The macroparticle was used as the particle source in the TWT interaction zone for the simulation of the beam wave interaction, which reduced the simulation time from 5.53h to 0.65h and improved the simulation efficiency. Compared with the original particle, both the K-means clustering algorithm simplifying the original particle and the mesh model simplifying the original particle greatly reduced the computational load of the interaction zone simulation. Compared with the grid model, The simulation results of the beam-wave interaction of macroparticles obtained by using the K-means clustering algorithm are closer to those of the beam-wave interaction using the original particles. By adjusting the cathode divergence angle and the distance between the anode and cathode of the electron gun of a certain type of TWT, the simulation results show that when the divergence angle is adjusted within the range of 0-1°, the larger the divergence angle, the larger the radial root mean square emittance value, the worse the laminar properties of the electron beam, and the power of the output signal of the TWT decreases. When the distance between the anode and cathode is adjusted within the range of 0.8-1.6mm, the simulation results show that when the parameter used to characterize the laminar properties property of the electron beam, namely the radial root mean square emittance, decreases from 2.51 mm·mrad to 2.22 mm·mrad, the laminar properties of the electron beam has been improved. The output power of the TWT has increased from 328.34 W to 414.10 W, and the operating frequency bandwidth with an output power greater than 300 W has been expanded from 3 GHz to 5 GHz. Therefore, the particle simplification model using the K-means clustering algorithm improves the simulation efficiency of the beam wave interaction. Based on the influence of the laminar properties of the electron beam on the performance of the TWT, the structural parameters of the electron gun can be optimized.