Environment-friendly mordant, hair dye and hair dyeing method

The invention discloses an environment-friendly mordant, a hair dye and a hair dyeing method. The environment-friendly mordant contains a C-O bond and comprises a mordant I, a mordant II and a mordantIII, wherein the mordant I is a chitosan-citric acid or malic acid aqueous solution; the mordant II is a konjac glucomannan-citric acid or malic acid aqueous solution; and the mordant III is a carboxymethyl cellulose sodium-citric acid or malic acid aqueous solution. The environment-friendly hair dye is prepared from pure-natural color sources completely. According to the environment-friendly mordant, the hair dye and the hair dyeing method, during hair dyeing, the hair dyeing effect obtained is optimal through using the mordant firstly, and then using a dyeing solution; different dyeing effects can be achieved through blending a coloring agent; and both raw materials of the hair dye and raw materials of the mordant are natural edible materials, so that the hair dye and the mordant are environmentally friendly, p