Abstract: In order to deeply investigate the antioxidant potential of essential oil from PK-type Perilla frutescens leaves, an essential oil with a content of perilla ketone higher than 40% was screened out by using the gas chromatographic analysis (GC) technology. Then, the chemical composition of the essential oil was further identified by using the GC-MS technology, and the antioxidant activity in vitro of the essential oil was analyzed, which provided a scientific basis for the development and utilization of the essential oil from PK-type Perilla frutescens leaves in the field of antioxidation. The results showed that there were 17 kinds of chemical components with the content of more than 0.5% in the essential oil from Perilla frutescens, all of which were terpenes and their derivatives, accounting for 89.72% of the total content of essential oil. The components with higher content were perilla ketone (44.98%), isoegomaketone (13.06%) and β-caryophyllene (10.53%). The experimental results of antioxidant activity in vitro showed that: the essential oil from PK-type Perilla frutescens leaves had scavenging ability to both DPPH and ABTS radicals, with IC₅₀ values of 7.00 and 2.66 mg·mL⁻¹, respectively. It also had certain iron reduction ability and total antioxidant capacity, with the RP_{0.5 AU} values of 11.96 and 1.83 mg·mL⁻¹. It was shown that all the above antioxidant activity indexes of the essential oil from PK-type Perilla frutescens leaves were positively correlated with the concentration.