This paper firstly determines the main factors affecting its the efficiency of multi-injection electron beam introduction and preliminary structural parameters through theoretical analysis. Secondly, the Ka-band relativistic multi-beam diode model is established by three-dimensional particle simulation software to optimize the structural parameters. The final efficiency of electron beam introduction can reach 89%. An experimental study on the generation and transmission of electron beams was carried out to verify the results of particle simulation. Under the condition of electron beam voltage 502 kV, beam current 4.34 kA, axial magnetic induction strength 0.76 T, the electron beam introduction efficiency reached 72%. The electron beam pattern obtained by electron beam bombardment of the nylon target indicates that the shape of the electron beam is not distorted during generation and transmission. The generated electron beam diameter is about 2 mm. The simulation and experimental results show that the designed high-current multi-beam diode can generate high-quality electron beams and achieve efficient electron beam introduction.