The study was carried out to analyze the relationship between analysis of antioxidant activity and the level of functional components according to particle size of corn silk. Particle size was classified into 5 groups. By particle size distribution and color difference, the total phenol content and DPPH radical scavenging activity were observed. The particle sizes of corn silk were 199.17 ㎛, 178.27 ㎛, 85.48 ㎛, 27.4 ㎛ and 20.97 ㎛, respectively. The lightness of colored pigments was increased when the particle size was decreased. The contents of free sugar (fructose, glucose, galactose, sucrose, and maltose) of corn silk were analyzed using a HPLC. The total phenol contents by the particle sizes of corn silk were 2.01 mg/g, 2.02 mg/g, 2.06 mg/g, 2.26 mg/g and 2.26 mg/g, respectively. DPPH radical scavenging activities of samples were 21.00%, 21.75%, 22.90%, 24.35% and 23.67%, respectively. Antioxidative activities of Trolox and Fe(II) in corn silk were measured by ferric reducing antioxidant power (FRAP) assay and Trolox equivalent antioxidant capacity (TEAC) assay. TEAC values of samples were 2.36 μmol TE / g dw, 2.81 μmol TE / g dw, 3.20 μmol TE / g dw, 3.36 μmol TE / g dw, and 3.44 μmol TE / g dw, respectively. FRAP values of samples were 11.67 μmol Fe(II) / g dw, 12.80 μmol Fe(II) / g dw, 13.43 μmol Fe(II) / g dw, 13.85 μmol Fe(II) / g dw and 15.95 μ mol Fe(II) / g dw, respectively. Total phenolic content and antioxidantive activities based on FRAP assay and TEAC assay were increased with decreasing particle size. In addition, DPPH radical scavenging activity was also increased. A significant correlation was also noted between DPPH radical scavenging activities and the content of phenolic compounds.