The invention belongs to the field of pharmaceutical chemical engineering, and particularly relates to a synthesis method of 16-hydroxy-9-ene-hexadeca-carboxylate. The method comprises the following steps: 1) adding polyhydroxy fatty acid used as an initial raw material for reaction into a single-neck reaction flask, adding silicone oil and raw acid carboxylate, and controlling the synthesis reaction temperature at 50-120 DEG C and the reaction time at 2-8 hours in a nitrogen protective atmosphere; 2) further adding an olefination reaction catalyst, and controlling the olefination reaction temperature at 110-180 DEG C and reaction time at 3-8 hours; and 3) cooling to room temperature, adding a right amount of H2O, performing stirring hydrolysis for about 30 minutes, then regulating the pH value to 5.0, extracting with ethyl acetate, drying with anhydrous sodium sulfate, and performing rotary evaporation to obtain the crude product 16-hydroxy-9-ene-hexadeca-carboxylate. The method is simple to operate, reagents involved in the reaction are environment-friendly, and the target product is simple to separate and purify.