The invention relates to a
cyanide-free
copper-
zinc alloy electroplating solution and a preparation method thereof. The
electroplating solution consists of the following components in percentage by weight: 1-60 percent of complexing agent, 0.3-10 percent of
copper salt, 0.2-10 percent of
zinc salt and the balance of water, wherein the general formula of the complexing agent is MxHyPnO(3n+1)Rz; M is any one or multiple in
alkali metal ions and NH<4+>; R is acyl; the general formula of the
copper salt is Cux / 2HyPnO(3n+1)Rz; the general formula of the
zinc salt is Znx / 2HyPnO(3n+1)Rz; x, n and z are positive integers; y is 0 or a positive integer; x+y+z is equal to n+2. The
cyanide-free copper-
zinc alloy electroplating solution is prepared by mixing the complexing agent, the
copper salt, the zinc salt and water, the complexing capacity of the complexing agent is high, the complexing constant of copper ions can be 10<26-27>, and the complexing agent is far superior to a conventional complexing agent in the prior art. The stability of the
electroplating solution prepared from the complexing agent is greatly improved, the quality of the electroplating solution is high, when the
cyanide-free electroplating solution is used for pre-plating, main salt
metal ions in the electroplating solution are not subjected to a replacement reaction with a
metal base material, a loose replacement layer structure is not formed, and the quality of the electroplating layer is greatly improved.