A lock system includes a locker device and a USB key. The locker device includes a first USB connector, a password input unit and a control unit. The USB key includes a second USB connector for connection to the first USB connector, a memory unit, and a decrypting unit. The memory unit is configured for storing a password. The decrypting unit includes a password identification unit configured for determining whether a password inputted into the password input unit matches the password stored in the memory unit and producing a decrypting instruction if the inputted password matches the stored password. The locker device is configured for transmitting the inputted password to the USB key. The USB key is configured for transmitting the decrypted instruction to the locker device through the connected first and second USB connectors to enable the control unit to unlock the locker device.