Preparation method of red-light blue metal phthalocyanine dye

The invention provides a preparation method of a red-light blue metal phthalocyanine dye. The preparation method comprises that metal phthalocyanine and chlorosulfonic acid are mixed and heated and undergo a reaction; reaction products are added with thionyl chloride; the mixture is cooled and is neutralized until a pH value of the mixture is 7; the neutralized mixture is added with ammonia water and reacts to produce a sulfamide group-containing metal phthalocyanine product; and the sulfamide group-containing metal phthalocyanine product is subjected to desalination and concentration and then is added with an assistant. The preparation method has the advantages that through control of reaction parameter conditions, the red-light blue metal phthalocyanine dye having good stability and good solubility is obtained; the problem that a red-light blue metal phthalocyanine dye obtained by the prior art has poor performances is solved; and the preparation method has simple processes, can be realized easily and has a good application prospect.