This simple intelligence password lock is based on MCU AT89C51, in addition, password saving, the row or column type keyboard, estate manifestation, the sound and light alarm, the LCD manifestation circuit and so on. The password saving circuit adopt I2C BUS of EEPROM memorizer AT24C01, and assurance while dropping the electricity the password information does not lose. The MCU is a control centre of the whole system. It is in addition to completing to read the password, compare password, save password, handle the false password, display an so on, still carrying out with the keyboard and LCD interface function. The customer can import the password with the keyboard, the password can display, also the customer can modify the password. At three times importing password after, it will give an sound and light alarm, and lock the keyboard.