The invention relates to a high-accuracy zinc base alloy electrode wire. Components in a shell layer comprise, by weight, 70.5%-95% of Zn, 2.5%-27% of Cu, 0.02%-4.0% of X, 0.002%-0.4% of Y and inevitable impurities brought in by raw materials. X is any two kinds of metal from Ni, Ag, Cr, Si and Zr, the content ranges of the two kinds of metal are both 0.01%-2.0%, Y is any two kinds of elements of Ti, Al, Co, B and P, and the content range of the two elements are both 0.001%-0.2%. The epsilon phase content in the shell layer structure is over 80% by weight, the balance is a gamma phase or an eta phase, and epsilon phases are evenly distributed on the surface of core materials. Meanwhile, the invention relates to a preparing method of the electrode wire. Compared with the prior art, a metal workpiece subjected to cutting processing by the electrode wire is high in surface smoothness and good in surface quality, accordingly, cutting accuracy is high, meanwhile, the electrode wire preparing technology is simple, operability is high, the number of manufacturing steps is small, and large-scale and automatic production can be achieved easily.