The invention discloses a mechanical logic device, a mechanical digital input device with the mechanical logic device and a digital lock. The mechanical logic device comprises a mixed dibit device. By means of the mechanical logic device, the mechanical digital input device with the mechanical logic device and the digital lock, a preset data password is easily, conveniently and safely set outside. The mechanical digital input device also solves the problem of mechanical digital and electronic digital mixed input, thereby being particularly suitable for a password input device in an important occasion. The digital lock is applicable to various locks, and particularly applicable to door locks in places such as school dormitories and offices with large staff mobility. A movable assembly with the adjustable position is adopted in the mechanical logic device, the application range of the mechanical logic device in industrial control is expanded, and the mechanical logic device is particularly convenient to apply in a site where a control program needs to be changed.