The invention discloses a safe authentication method of a CPU card entrance guard reader capable of implementing bidirectional authentication. The authentication method is specially designed for requirement characteristics of application of an entrance guard system, an authentication step between the card reader and a CPU card is simplified, meanwhile, a bidirectional authentication mode between the CPU card and the card reader is realized, safety is greatly improved, the technical difficulty of card copying is greatly increased, a plurality of groups of keys are used, encipherment protection modes are selected randomly, and risks of violent breaking of the keys are greatly reduced; and meanwhile, steps of authenticating and reading card entrance guard numbers are simplified, and an authentication process is simplified into a group of interaction commands by card reset information.