Negative-ion based neutral beam injection is an indispensable auxiliary heating method for future large tokamak devices. The acceleration grid power supply in the neutral beam system requires an output voltage of -200 kV and a power of 5 MW, and often faces special conditions of sudden short-circuit and disconnection of the load. The design of the high-voltage components is still missing in the research of the acceleration grid power supply. The insulation design of the high-voltage components is a critical part of the power supply development process. In this paper, the circuit parameters of the step-up transformer, high-voltage rectifier and high-voltage filter of the high-voltage part of the power supply are calculated according to the power supply index and the characteristics of the special working conditions, the engineering design based on oil-immersed insulation of these parts is also carried out, and the insulation is verified by finite element simulation analysis. The simulation results show that the maximum electric field strength in these components is 16.22 kV/mm, which is less than the transformer oil breakdown field strength and has 2 times the insulation margin. The structural design of the high-voltage components in this paper can meet the insulation requirements of the power supply.