Abstract: Essential oils of Forsythia mandschurica Uyeki fresh flowers were extracted by simultaneous distillation extraction(SDE) method. Chemical composition of essential oils were analysized by gas chromatography-mass spectrometry(GC-MS). The effects of different solvents on the results were studied. The results showed that the yield of essential oil of F. mandschurica Uyeki fresh flower extracted by SDE light petroleum method was 0.69%.28 components were identified from it. The highest GC content compound was pentacosane(28.65%), and the second was Z-9-tricosene(27.82%). The yield of essential oil of F. mandschurica Uyeki fresh flower extracted by SDE hexane method was 0.81%.44 components were identified from it. The highest GC content compounds was Z-9-tricosene(47.16%). The Z-9-tricosene was housefly sex attractant, and other aromatic compounds were myristic aldehyde(0.97%), caryophyllene(0.05%), etc.