The dichloromethane fraction of Ferula ferulaeoides was analyzed by GC and GC-MS, and thirty-four compounds were identified. The main component in the fraction, guaiol (37.0%) was separated by chromatographic methods and identified from spectroscopic data, including 1H and 13C NMR, and X-ray crystallographic diffraction. Guaiol showed significant inhibition of aphids at a concentration of 70 mg/L. It also showed good contact activities against the 4th instar larvae of Mythimna separate and 3rd instar larvae of Plutella xylostella, with LD50 values of 0.07 and 8.9 mg/larva, as well as fumigation activity against the 4th instar larvae ofM. separata and adult Musca domestica, with LC50 values of 3.5 microL/L and 16.9 microL/L, respectively.