In this work, the irregular TA1 powder was spheroidized by DC arc thermal plasma. Metallographic microscope, scanning electron microscope, particle size analyzer, Hall flowmeter and oxygen-nitrogen analyzer were used to study the particle size of raw material powder and the power of plasma generator in the process of spheroidization, and the effects on the microstructure, particle size, sphericity, fluidity, bulk density and oxygen content of the spheroidized powder. The results show that the irregular TA1 powder was spheroidized into solid spherical powder with uniform particle size after thermal plasma spheroidization. The surface was coated with a layer of nanoparticles. After spheroidization, the internal structure of the powder changed from the initial equiaxed α phase to the long strip α phase. The average particle size and oxygen content of TA1 powder decreased and the sphericity increased by thermal plasma spheroidization. The smaller the particle size of raw powder and the greater the power of plasma generator, the smaller the average particle size of spheroidized powder and the higher the sphericity, too small particle size of raw material powder and too high power of plasma generator will lead to the increase of nano-particle content in the powder after spheroidization, the deterioration of powder fluidity and the decrease of bulk density. After removing nanoparticles can improve the fluidity of powder.