Abstract: A simple synthesis of "Queen substance"(trans-9-Oxo-dec-2enoic acid)was reported.Monobromination of 1,6-hexandiol followed by protection with 3,4-dihydro-2H-pyran afforded compound 2.After addition between Grignard reagent of compound 2 and acetaldehyde,deprotection and oxidation by pyridinium chlorochromate(PCC),a Kaoevenagle reaction finally provided the "Queen Substance" in 25.55% overall yield.