Improved preparation method of indacaterol

The invention provides an improved preparation method of indacaterol or a salt thereof, which adopts formic acid or ammonium formate as a hydrogen source to prepare indacaterol in a catalytic hydrogenation debenzylation process, omits harsh conditions required by a conventional method taking hydrogen as a hydrogen source, reduces requirements on equipment, and is simple and convenient and higher in safety; generated excessive hydrogenation impurities are few, and the product purity is higher; reaction liquid is stable, the process is more controllable, and the method is more suitable for industrial production. 本发明提供一种茚达特罗或其盐的改进制备方法，该方法在催化氢化脱苄工艺中采用甲酸或甲酸铵作氢源制备茚达特罗，革除了以氢气作氢源的常规方法需要的苛刻条件，对设备的要求降低、方法简便且安全性更高；产生的过度氢化杂质少、产品纯度更高；反应液稳定、工艺更加可控，更适于工业化生产。