The invention discloses a bidirectional communication combination lock. The bidirectional communication combination lock comprises a key microprocessor 1, a key programming interface 2, a key clock module 3, a key power supply module 4, a key button module 5, a key communication module 6, a lock microprocessor 7, a lock programming interface 8, a lock clock module 9, a lock power supply module 10, a lock communication module 11, an input module 12, a display 13, an indicating lamp 14, a loudspeaker 15, and a mechanical lock body 16. According to the bidirectional communication combination lock, ID data of a key can be encrypted to random data which changes in real time and is sent to a lock, the ID data is decrypted by the lock and encrypted and sent to the key, the key decrypts the ID data, unlock data is encrypted and sent to the lock, and the lock decrypts an unlock password and performs unlocking; the key and the lock are both provided with standby emission elements and receiving elements, in the normal communication condition, one element works, the other element is standby, and automatic switching can be realized; and in this way, the lock has great security and stability.