Disclosed are a compound ambroxol hydrochloride composition and a preparation method therefor, which relate to the field of medicine. 0.1%-99.9% by mass of ambroxol hydrochloride and 99.9%-0.1% by mass of scopolamine serving as main ingredients and mannitol are added into water for injection; stir to dissolve, then adjusting to pH 5.0 by adding an NaOH solution; add 0.1% of activated carbon with stirring for 30 minutes; filter out the activated carbon, and then filtering the liquid with 0.45 µm and 0.22 µm microporous filter membranes; fill the filtered liquid into a large plate or a vial; send into a lyophilizer, cool to -40°C, and hold the temperature for 2 hours; warm to -5°C to 0°C slowly to lyophilize the liquid, heat to 35°C, and hold the temperature for 3 hours; take out of the lyophilizer after lyophilizing to obtain a lyophilized powder injection containing ambroxol hydrochloride and scopolamine; crush the lyophilized powder injection under a sterile conditions, and sieve with a 180-mesh sieve to obtain sterile lyophilized powder containing ambroxol hydrochloride and scopolamine; and prepare various dosage forms by using the lyophilized powder as a raw material. The preparation method provided by the present invention is scientific and reasonable, and is convenient for preparing various dosage forms.