The invention discloses a method used for synthesizing 1, 9-decadiene using a fixed bed reactor. The method comprises following steps: 1, 10-decanediol and a higher fatty acid are mixed and are subjected to esterification reaction; an obtained esterification intermediate is introduced into the fixed bed reactor drop by drop for esterification cracking, wherein a filling material is introduced intothe fixed bed reactor, the temperature in the fixed bed reactor is controlled to be 330 to 370 DEG C, and the standing time of the esterification intermediate in the fixed bed reactor is controlled to be 2.5 to 4h; a 1, 9-decadiene crude product obtained through reaction is discharged through the top of the fixed bed reactor in gas form, is subjected to condensation, and is collected in liquid form; the collected liquid product is introduced into a reaction container through flowing for collection; the 1, 9-decadiene crude product is subjected to underpressure distillation so as to obtain 1,9-decadiene. The reaction selectivity is as high as 95%, and the yield is as high as 90%.