The thermal behavior of ethylene-tetrafluoroethylene copolymer (ETFE) and poly(vinylidene fluoride) (PVDF) blends was investigated by thermogravimetic analysis, differential scanning calorimetry, tensile test, scanning electron microscopy, and dynamic mechanism analysis. In this study, ETFE was used as matrix and blended with PVDF. Results showed that PVDF could promote the initial thermal decomposition temperature of ETFE without sacrificing other properties and slight changes in the maximum degradation rates of blends. Results were derived from an isoconversional method, where activation energy is represented as a function of the extent of degradation. Thermal degradation activation energies of material degradation were calculated based on the nonisothermal dynamic thermal kinetic model. The Ed of PVDF/ETFE (10%/90%) blend was 187 kJ/mol , which was higher than pure ETFE. Therefore, the blend had good thermal resistance.