The invention discloses a preparation method of a water-soluble ternary quantum dot and also discloses a preparation method of a water-soluble doped ternary alloy quantum dot and a novel quantum dot material. The novel quantum dot material is the Cu<+> or Ag<+> doped ternary alloy quantum dot prepared by the preparation method. The preparation method has the advantages that quick preparation of the doped ternary alloy quantum dot at room temperature is achieved, and a new method for preparing the alloy quantum dot based on water-phase ion exchange reaction is developed; the method requires simple equipment, is quick in doping and low in energy consumption, is easy to operate, is not dangerous and is convenient in raw material supply and low in raw material price; the ratio of cations of the ternary quantum dot can be flexibly adjusted by the doping method, thus achieving the effect of regulating the optical-electrical characteristics of the ternary quantum dot; and the obtained doped ternary quantum dot has good fluorescence characteristic and stability.