The invention relates to a production line of black sugar rich in polyphenol. Squeezing equipment, impurity removal and filtration equipment, a preliming cylinder, a tubular heat exchanger and a steam heater of the production line are sequentially connected, a lime milk storage cylinder is connected with the preliming cylinder, the outlet of the steam heater is connected with the inlet of a primary ceramic membrane, the concentrated solution outlet of the primary ceramic membrane is connected with the preliming cylinder by virtue of full charging equipment and a plate-and-frame filter press, and the clear solution outlet of the primary ceramic membrane is connected with the inlet of a secondary nanofiltration membrane; the concentrated solution outlet of the secondary nanofiltration membrane is connected with black sugar packaging equipment by virtue of vacuum evaporation concentration equipment, constant pressure concentration equipment, a nucleation box and a moulding die sequentially; and the clear solution outlet of the secondary nanofiltration membrane is connected with a white granulated sugar production line. The production line of the black sugar rich in polyphenol has the advantages that two stages of ceramic membranes with different membrane pore diameters are adopted for filtering sugarcane juice, concentrated juice filtered by two stages of membranes is adopted for producing the black sugar rich in polyphenol, a functional ingredient, namely polyphenol, in the concentrated juice obtained by virtue of the two stages of membranes is effectively enriched, enrichment efficiency is improved by 4-8 times compared with the traditional production technology, and quality and nutritional value of the black sugar are improved.