Effects of supersonic treatment (ST), instant controlled pressure drop (ICPD) treatment and steam blanching treatment (SBT) on functional components and antioxidant activity of Prunus mira Koehne were investigated. Diverse methods, including DPPH, ABTS and FRAP, were used to evaluate antioxidant activity of functional components extracted from Prunus mira Koehne. Relationship between contents of antioxidant substances and antioxidant activities was analyzed by linear fitting method. Compared with the control group, ST induced a significant decline in contents of antioxidant substances and their antioxidant capacity except pectin (P<0.05); ICPD could increase contents of polysaccharide and pectin and improve their antioxidant activities. However, ICPD had adverse effects on polyphenol and flavonoid；SBT induced a remarkable increase in contents of functional components and enhanced their antioxidant capacity (P<0.05). Moreover, SBT reserved more chlorogenic acid, catechin and neochlorogenic acid than other treatment method. Extacts of Prunus mira Koehne had the highest contents of polyphenol \[(15.05±0.04) mg GAE/g DB\] when treated with steam blanching for 1 min. As steam blanching processing time increased to 3 min, the contents of flavonoid, polysaccharide and pectin of Prunus mira Koehne reached their peak value, (67.40±0.74) mg RE/g DB, (143.95±0.37) mg GE/g DB and (61.81±1.10) mg GalA/g AIR, respectively. Line fitting analysis (P<0.05) presented a positive correlation between contents of polyphenol, flavonoid, polysaccharide and their DPPH radical scavenging activity (R²=0.756, 0.991, 0.820, respectively) . Above all, SBT is supposed to be an effective pretreatment before further processing for Prunus mira Koehne .