Improving the dispersibility and compatibility of nanomaterials in water-borne epoxy resins is an important means to improve the protection ability and corrosion resistance of coatings. In this study, glycine-functionalized Ti3C2Tx (GT) was used to prepare an epoxy composite coating. The results of Fourier transform infrared spectroscopy and X-ray diffraction showed that glycine was successfully modified. The scanning electron microscopy and transmission electron microscopy results showed that the aggregation of Ti3C2Tx was alleviated. Electrochemical impedance spectroscopy test results show that, after 60 days of immersion, GT coating still shows the best protection performance, and the composite coating |Z|f = 0.01 Hz is 3 orders of magnitude higher than that of the pure epoxy coating. This is mainly because, after adding glycine, the -COOH group on the surface of glycine binds to the -OH group on the surface of Ti3C2Tx, improving the aggregation of Ti3C2Tx itself. At the same time, the -NH group of glycine can also participate in the curing reaction of epoxy resin to strengthen the bonding strength between the coating and the metal. The good dispersion of GT in epoxy resin makes it fill the pores and holes left by epoxy resin curing and strengthen the corrosion resistance. The easy availability and green properties of glycine provide a simple and environmentally friendly method for the modification of Ti3C2Tx.