The invention relates to an ambroxol hydrochloride composition for injection and a preparation method thereof. The composition contains ambroxol hydrochloride and mannitol. The preparation method comprises the steps of: (1) preparing: placing the ambroxol hydrochloride and the mannitol in a preparation tank according to the proportion of 1:(1-4), adding water for injection, and stirring to ensure that the ambroxol hydrochloride and the mannitol are completely dissolved and uniformly mixed; (2) aseptically filtering, split-charging and plugging half; and (3) freezing and drying in vacuum to obtain the ambroxol hydrochloride composition. The ambroxol hydrochloride composition provided by the invention has the advantages of simple prescription, advanced process, uniform and stable quality, completely moisture dryness and better re-solubility.