The invention belongs to the technical field of drug synthesis, and particularly relates to a synthesis method of indacaterol and salt derivatives thereof and intermediate for the synthesis. The synthesis method of indacaterol comprises the following steps: carrying out amine alkylation and deprotection reaction, in a one-pot manner, on a compound shown as a general formula IV and a compound shownas a formula V serving as raw materials to obtain a compound shown as a formula I, wherein the reaction equation is shown as the specification; wherein R is a silane protecting group. According to the technical scheme provided by the invention, by carrying out Boc protection on the amino group, polyalkylation on the amino group is ingeniously avoided, so that under the condition that both the hydroxyl group and the amino group have proper protection, the alkylation reaction effectively avoids the generation of by-products; after the alkylation reaction, hydroxyl and amino deprotection can bedirectly carried out, so that the multi-step reaction is completed in one reactor; according to the method, the intermediate purification and separation process is omitted, the reaction yield is increased to the maximum extent, and the production cost is reduced.