In order to explore the effect of different irons on the fruit quality of wine grapes, as well as the phenolic acids and proanthocyanidins of the peel, “Cabernet Sauvignon” was taken as the research object. Ferrous sulfate, EDTA-Fe, ferric citrate, ferric gluconate and ferric sugar alcohol were sprayed between the coloring periods, and the foliar sprayed water was used as the control. The results showed that foliar spraying of iron would increase the fruit sugar-acid ratio and 100-grain weight; iron spraying would up-regulate the content of phenolic acid monomers, among which EDTA-Fe and ferric citrate had significant up-regulating effects, but all iron treatments had a significant effect on the increase. The content of caffeic acid and chlorogenic acid was down-regulated; the content of proanthocyanidin monomer was up-regulated by iron spraying, and the content of proanthocyanidin monomer was significantly up-regulated by ferric citrate treatment. Foliar spraying of ferric citrate not only balanced the sugar-acid ratio of the fruit, but also increased the content of phenolic acid and proanthocyanidin in the grape peel, which further improved the quality of the grapes and helped to increase the flavor of the wine.