The invention belongs to the technical field of chemical synthesis, and specifically relates to a synthesis method of tamsulosin hydrochloride. According to the synthesis method, benzene sulfonic amide shown as a formula (II) and bromine ether shown as a formula (III) are in a condensation reaction in an aprotic polar solvent in the presence of an acid-binding agent to generate a condensation compound intermediate shown as a formula (IV); the condensation compound intermediate is in organic solvent, in the presence of a catalyst, hydrogen is introduced into the organic solvent under certain pressure so as to hydrogenate the condensation compound intermediate, then, the R-tamsulosin free alkali shown as a formula (V) is obtained, and the R-tamsulosin free alkali further is subjected to a salt formation reaction with hydrochloric acid in an organic solvent C to produce the tamsulosin hydrochloride shown as a formula (I). In the reaction process for preparing the tamsulosin hydrochloride through the synthetic route provided by the invention, the phenomenon that bimolecular bromide and amine react with each other to generate a disubstituted by-product is avoided, and the obtained tamsulosin hydrochloride has high product purity and high yield; according to the synthesis method, the reaction conditions are moderate, and synthesis is convenient to finish.