The invention relates to a method for synthesizing an astaxanthin intermediate. The method specifically comprises the following steps: 1) adding lithium into liquid ammonia to implement a reaction, introducing acetylene to synthesize acetylene-based lithium, replacing the liquid ammonia with an organic solvent, and adding 1-butene-3-ketone to implement a reaction continuously, so as to generate 3-methyl-1-amylene-4-alkyne-3-lithium alkoxide; 2) adding lithium into the liquid ammonia to implement a reaction, and further adding the product obtained in the step 1) to generate 3-methyl-1-amylene-4-alkynyl based lithium-3-lithium alkoxide; 3) performing a condensation reaction on the product obtained in the step 2) with heterogeneous diketone so as to generate a condensation compound; 4) performing acid hydrolysis on the condensation compound obtained in the step 3), and treating with a reduction triple bond so as to obtain 2,4,4-trimethyl-6-hydroxy-3-(3-methyl-1,4-dipentene-3-hydroxy)-2-cyclohexenone; 5) enabling 2,4,4-trimethyl-6-hydroxy-3-(3-methyl-1,4-dipentene-3-hydroxy)-2-cyclohexenone to react with hydrobromic acid and triphenylphosphine in sequence, thereby finally generating the astaxanthin intermediate. By adopting the method, multiple times of introduction and repeated hydrolysis of extra protection groups are avoided, so that the raw materials are saved, and the preparation route is simplified.