The invention relates to the technical field of vat dye dyeing, in particular to an anolyte for indirect electrochemical dyeing of vat dyes, the electrolyte of which includes sulfite, pyrosulfite, dithionite or thiocyanate at least one. The present invention adopts an electrolyte with excellent electrical conductivity and less side reactions and weak reducibility, and selects sulfite, pyrosulfite, dithionite or thiocyanate as the anode electrolyte, which has a strong ability to conduct electrons, and can be used on the anode. The reaction is fast, the product is sulfate, clean and environmentally friendly, the dyeing process under this system is simple, the reduction time is shortened, and the current efficiency is high, which is conducive to the realization of industrial production and has good application prospects. It solves the traditional anolyte such as sulfuric acid and other electrode corrosion Serious, poor safety, long recovery time, low current efficiency and other problems.