The invention discloses a two-dimensional code authentication method, a two-dimensional code authentication platform and a two-dimensional code authentication system, and relates to the field of mobile Internet. To improve the using safety of two-dimensional codes, a two-dimensional code client is used to scan a two-dimensional code image to obtain encrypted information, the encrypted information is added with a digital signature and then sent to the two-dimensional code authentication platform, and the two-dimensional code authentication platform authenticates the legitimacy of the digital signature and decrypts the encrypted information to ensure the application legitimacy. The two-dimensional code authentication method, the two-dimensional code authentication platform and the two-dimensional code authentication system of the invention are applicable to two-dimensional code applications with high requirement on safety, such as commodity purchase, identity identification, and electronic documents.