Synthetic process of vat blue RSN

The invention belongs to the dye processing technology field, in particular to a new synthesis technology for a vat blue RSN dye. The invention utilizes a new solvent for condensation reaction, realizes one step reaction without the prior processes of refinement and oxidation, and obtains high purity vat blue RSN raw dye with high yield; the yield of the prior technology only reaches 70 percent, while the yield of the new technology with one step condensation reaction can reach over 90 percent, which not only greatly reduces production cost and improves product quality, but also tremendously reduces pollution and emission of three wastes.