Abstract: The magneto-conductance effect is used to describe the changes of the current of the OLED (organic light-emitting diode), whose organic functional layer has no ferromagnetic material. In the presence of external magnetic field, the current in the device would be changed significantly since the diode is sensitive to the magnetic field. The magnitude of the magnetic field could be got through comparing the value of current with the curve of B-I which was measured and stored in the computer. Therefore, this special effect could be used to produce the new type of sensor of magnetic field. If the complex excited state and the process of spin relaxation in the OLED could be studied thoroughly, the new luminescence materials could be synthesized and the new structure could be designed which can help us improve the performances of OLED. Furthermore, the magnetic field can have a significant influence on the excited state process in the diode which can be a tool to study the underlying mechanisms of OLED. Up to now, the tremendous progress has been made in the field of magneto-conductance effect. This article summarized the background, progress, the major achievement and the possible microscopic mechanism in the field of magneto-conductance effect. In addition, the prospect in the field of magneto-conductance effect has been made.