Purpose: To conduct gas chromatography-mass spectrometric (GC-MS) analysis of the chemical compositions of dill seed essential oil (DSEO) obtained by supercritical CO2. Methods: The impact on extraction yield were examined by single factor test, the particle size of dill seed, extraction temperature, time, pressure, as well as CO2 flux. The best extraction conditions were obtained by an orthogonal test. The chemical configurations of essential oil were examined by GC-MS analysis. Results: The optimal extraction conditions included an extraction time of 120 min, particle size of 60 mesh, CO2 flow of 25 L/h, temperature of 40oC, and pressure of 20 MPa. Under these conditions, the yield of essential oil was 6.7 %. Out of 38 recognized compounds, the main ones were D-carvone (40.36 %), D-limonene (19.31 %), apiol (17.50 %), α-pinene (6.43 %), 9-octadecenoic acid (9.00 %) as well as 9,12-octadecadienoic acid (2.44 %). Conclusion: A total of 38 constituents of the essential oil obtained by supercritical CO2 were identified. The findings may provide a theoretical basis for comprehensive utilization of dill seed essential oil (DSEO) from China.