The invention discloses a collaborative signature and decryption system based on an SM9 algorithm. The collaborative signature and decryption system comprises a first communication party, a second communication party and auxiliary equipment. The data to be signed is signed in a cooperative signature mode, and an intruder cannot forge the target signature data on the premise that the intruder doesnot know the first private key component and/or the second private key component. Moreover, the second private key component stored in the auxiliary equipment cannot be leaked, so that the second private key component cannot be leaked by utilizing the scheme of the embodiment of the invention, the security of the private key of the user is ensured, the target signature data cannot be forged, and the security of the user when the user finishes the corresponding service by utilizing the Internet is ensured. Because the second private key component is not leaked, the intruder cannot obtain correct target decryption data, thereby ensuring the security of the user when the user finishes the corresponding service by using the Internet.