An externally-used solution containing chlorine dioxide for promoting hair growth is composed of chlorine dioxide or its precursors, pH regulators, medical solvents and plant extract in a certain weight ratio. The product may take the forms of a single solution containing chlorine dioxide or several solutions containing a chlorine dioxide precursor. The safety and effective oxidation sterilization and tissue regeneration ability of chlorine dioxide are introduced into the solution system for promoting hair growth, and the steps of removing hair loss factors, stimulating the growth of hair follicles, anti-inflammatory and anti-dandruff are done synchronously. Complemented medical solvents and plant extracts will change alopecia environment.