The invention discloses a heterogeneous network end-to-end authentication secret key exchange method based on a space-sky information network. The method includes a mobile terminal registering step, a secret key establishment request step, an end-to-end authentication secret key exchange step and a password update step, which are conducted in sequence. A common session key can be established for two mobile terminals in two different trust domains while the identities of the mobile terminals are verified, so end-to-end secure communication is achieved. On the basis of symmetric encryption and the design of a Hash function, public key password operation that is time consuming is not used, so the method completely meets application demands of limited resources of the mobile terminals in a space-sky information network. The calculating cost of a server is low, and congestion will not occur due to frequent requests of the mobile terminals. Moreover, a dual-factor authentication mode of both an intelligent card and a password is adopted, so higher security is exhibited. Identity information of the mobile terminals is hidden in public information, so the mobile terminals are anonymous in identity.