The invention discloses a biphase stainless steel, which is especially suitable for the steel used for coinage. The biphase stainless steel comprises the chemical components by weight percentage (wt percent) as follows: C and N are less than or equal to 0.12 percent, Si is less than or equals to 1.0 percent, Mn is less than or equals to 6.0 percent, P is less than or equals to 0.04 percent, S is less than or equals to 0.01 percent, Ni is 3.0 to 7.0 percent, Cr is 20.0 to 28.0 percent, Mo is 0 to 2.0 percent, W is 0 to 2.0 percent, binary master alloy that is Ag-Cu is 0.10 to 1.0 percent, and the other weight percentage is composed of Fe and ineluctable impurities, wherein, the ratio (that is Creq/Nieq) between Cr valent weight and Ni valent weight ranges from 3.0 to 3.8. The volume percentage of the biphase stainless steel in a cold-rolling annealed ferrite is 65 to 85 percent, and the saturation magnetic induction thereof is 0.7 to 1.0T. The biphase stainless steel has good heat formability, low hardness and good plasticity; the erosion resistance is better than the existing coinage stainless steel, and the anti-fake performance and the bacteria resistance performance are realized.