Abstract: Plasma Rotating Electrode Process (PREP) is one of the most important methods of manufacturing superalloy powder in China. The quality of powder is highly concerned in the field of Powder Metallurgy(PM). One kind of abnormal particles in nickel-based superalloy powder by PREP was observed, classified, and analyzed statistically in this paper. Research has shown that the abnormal particles which consist of powder and adhering sublimation, slag, ceramic and organic impurities exist in the superalloy powders. The formation of abnormal particles has a close relationship with the purity of master alloys, properties of inclusions as well as powder atomization parameters. The ability of removing abnormal particles by screening and electrostatic separation was associated with the size, shape and chemical composition, physical properties(density, permittivity）of adhering inclusions. Compared with the screening process, the number of abnormal particles in 1kg powder sample reduce by 63% after electrostatic separation process. In 50-150μm finished powders, the abnormal particles adhering slag account for 36% in residual inclusions, the particles adhering ceramic -4%, the particles adhering organic-11%.