Liquid carboxyl-terminated poly(butadiene-co-acrylonitrile)(CTBN)-epoxy resin(EP) prepolymers were prepared with different contents of CTBN.The chemical reactions between EP and CTBN were characterized by Fourier ransform infrared(FTIR) spectroscopy and gel permeation chromatography(GPC).The scanning electron micrograph(SEM) and dynamic mechanical analysis(DMA) of curing films showed phase separation,and the rubber particles were finely dispersed in the epoxy matrix.Mechanical properties analysis of curing films showed that impact strength and elongation at break increased significantly upon the addition of CTBN,indicating good toughness of the modified epoxy resins.Thermogravimetric analysis(TGA) showed that the incorporation of CTBN had little effect on the thermal stability of EP.Fusion-bonded-epoxy(FBE) powder coatings modified with CTBN-EP prepolymers were prepared.The experimental results demonstrate the ability of CTBN-EP prepolymers,toughening technology to dramatically enhance the flexibility and impact resistance of FBE coatings without compromising other key properties such as corrosion protection. Liquid carboxyl-terminated poly (butadiene-co-acrylonitrile) (CTBN) -epoxy resin (EP) prepolymers were prepared with different contents of CTBN.The chemical reactions between EP and CTBN were characterized by Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) and dynamic mechanical analysis (DMA) of curing films showed phase separation, and the rubber particles were finely dispersed in the epoxy matrix. Mechanical properties analysis of curing films showed that impact strength and elongation at break assigned significantly the addition of CTBN, indicating good toughness of the modified epoxy resins. Thermogravimetric analysis (TGA) showed that the incorporation of CTBN had little effect on the thermal stability of EP. Fusion-bonded-epoxy (FBE) powder coatings modified with CTBN-EP prepolymers were prepared.The experimental results demonstrate the ability of CTBN-EP prepolymers, toughening technology to slightly enhance the flexibility and impact resistance of FBE coatings without compromising other key properties such as corrosion protection.