Abstract: The anodic bonding in air between K₄ glass and Al is investigated in this paper．It is found that the linear thermal expansion coefficient plays an important role in anodic bonding．The welding ability and influencing factors are analyzed during the bonding process between Al and K₄ glass in air．Change in current has certain rule,which is described in this paper．The microstructure of the K₄ glass-Al interface is investigated,and the result indicates that the composition of the interface is formed by Al₂SiO₃ and some other kinds of compound substances made up by Si, Al,Zn,O,Na and so on．