Abstract: The cardanol diethers (CDE) was obtained from Williamson etherification of cardanol(CD) and 1,3-dibromopropane. Then the cardanol diethers-Mannich baseas curing agent (MBCDE) for epoxy resins was prepared from the Mannich reaction of CDE, paraformadehyde and diethylenetriamine. The chemical structure was confirmed by FT-IR and 1H NMR. N-Aminoethylpiperazine (AEP) was chose as a control to investigate the toughening properties of MBCDE. Thermogravimetric analysis (TGA), scanning electronic microscopy (SEM) and mechanical properties of the cured epoxies were also conducted to investigate the properties of the bisphenol A epoxy resin (DGEBA) cured by two curing agents. The TGA results showed that the maximum decomposition temperature of MBCDE was 351.6℃ and the sample had good thermal stability. The impact strength of cured AEP/DGEBA was 3.641 J/m, while the cured 80% MBCDE sample had an impact strength of 5.155 J/m, which was improved by 41.6%. SEM results indicated that there was phase seperation in the cured materials contained MBCDE.