This paper presents the design of an atmospheric pressure coaxial argon plasma generation device, which is suitable for the modification of nanoparticle materials. By analyzing the discharge phenomenon, electrical characteristics, and spectrum, the effects of varying applied voltages, gas flow rates, and screen mesh numbers on the discharge characteristics were examined. Experimental results indicate that as the applied voltage increases, the average discharge power also rises. The number of active particles in the argon plasma initially increases and then diminishes, peaking around 9 kV. Conversely, with an increase in gas flow rate, the average discharge power gradually diminishes, the number of active particles in the argon plasma gradually increases, and the discharge becomes more uniform. Furthermore, as the screen mesh number increases, the average discharge power gradually decreases. The number of active particles first increases and then decreases, reaching a maximum when the mesh number is 30, and the discharge is relatively uniform. In conclusion, taking all factors into account, it is recommended to choose an applied voltage of approximately 9 kV, a gas flow rate of 4 slm, and a screen mesh number of 30 for nanoparticle modification, as this combination is deemed the most optimal.