The invention provides an environment-friendly type polyester flexible cord immerging liquid, which comprises a first immerging liquid and a second immerging liquid and is prepared from the followingraw materials: the first immerging liquid comprises, by weight, 870-1000 parts of deionized water, 10-14 parts of epoxy resin, 35-45 parts of waterborne isocyanate and 10-15 parts of VP latex; and thesecond immerging liquid comprises RFL immerging liquid. According to the invention, a traditional single-bath impregnation system is improved, environment-friendly type materials are adopted, a smallamount of VP latex is added in single-bath, adhesion between single-bath and two-bath is enhanced, and adhesive force is increased. A polyester immerged flexible cord produced by the method has highadhesion with rubber and can be used for production of various forms of V belts, polywedge belts and synchronous belts. In addition, the cord has high adhesion retention rate and is storage tolerant.