Abstract: In order to study the efficient extraction technology of camphor tree essential oil and broaden its application range, the subcritical extraction of essential oil from Cinnamomum camphora leaves was optimized by orthogonal design experiment with 1, 1, 1, 2-tetrafluoroethane(R134a) as extraction solvent. The differences in chemical compositions and antimicrobial activity of essential oil from C. camphora leaves extracted by subcritical R134a extraction and the traditional steam extraction were compared. The results showed that the optimal parameters for subcritical R134a extraction of essential oil from C. camphora leaves were as follows: the particle size of the raw material obtained by crushing with 2 mm aperture sieve, the solid-liquid ratio of 6:1(L: kg), the extraction temperature of 45 ℃, the extraction time of 40 min/times, and the extraction for 4 times. Under this condition, the extraction ratio of essential oil was(2.87±0.08)%. GC-MS analysis of the two leaves essential oils obtained from steam extraction and subcritical R134a extraction identified 39 and 35 compounds, with the relative total peak areas of 99.97% and 99.91%, respectively. The chemical components of the two leaves essential oils were mainly alcohols and hydrocarbons, and borneol was the main chemical component in the essential oils. The relative peak area of borneol in steam extraction essential oil(64.29%) was greater than that of subcritical R134a-extracted essential oil(58.09%). The two kinds of leaves essential oils from leaves had different degrees of antimicrobial effect on plant pathogens. The antimicrobial activity of leaves essential oil extracted by subcritical R134a extraction on pathogenic fungi was better than that of essential oil extracted by steam extraction. The two essential oils from leaves had the highest antimicrobial rate against Phytophthora capsici, which were 71.74% and 62.87%, respectively.