Abstract: Intelligent instruments based on microcontroller are playing important role in industry.As the interface between human and machines,liquid crystal devices have the characteristics of low voltage,less power consumption,large quantities of information for display and their beautiful appearance.In many fields,LCD replaces tranditial display methods.In this paper,the characteristics and work mechanism of both characters LCD and AT89C2051 are explained.The author works out an interface technique of LCD block with AT89C2051.The technique makes the connection scheme easy and brief. It is useful in practice.