The invention belongs to the field of pharmaceutical preparations and in particular relates to a compound oral solution containing dextromethorphan hydrobromide and phenylephrine hydrochloride and a preparation method thereof. The dextromethorphan hydrobromide is clinically and widely used for treating various types of coughs, and phenylephrine is a vasoconstrictor and can be used for reducing respiratory mucosa edema and increasing drainage of sinus cavities; the compound oral solution preparation can be used for treating cough, nose or throat tickle, lacrimation and nasal congestion, which are caused by cold, and also can be used for reducing nasal passage swelling.