The invention discloses a marine biological solution for treating onychomycosis and paronychia and a preparation method thereof. The marine biological solution comprises the following components by weight percent: 1.5-2.5% of carboxymethyl chitosan, 3.0-4.0% of algal polysaccharide, 2.0-4.0% of mucopeptide-N-acetylmuramoylhydrolase, 6.0-9.0% of cecropin, 2.0-3.0% of glycerol, 1.0-4.0% of algae powder, and 73.5-84.5% of water. According to the invention, the marine biological solution for treating onychomycosis and paronychia is a non-toxic, colorless, odorless, non-irritant, non-corrosive and pollution-free green marine biological product, and has the advantages of convenience in use, high sterilization efficiency, wide bactericidal spectrum, high cure rate, short healing time and the like.