The liquefying and melting processes of the binary mixed system consisting of a new type of high energy density materials 3,4-dinitrofurazanfuroxan (DNTF) and pentaerythritol (PETN) were studied by pressure differential scanning calorimetry (PDSC). On the basis of PDSC characteristic values of DNTF/PETN systems with various mass ratios,the phase diagrams of liquefying temperature (T) versus composition (X) and apparent fusion heat (H) versus composition (X) were constructed. Results show that the compositions of the eutectic system of DNTF/PETN are obtained to be 68.20/31.80 (molar fraction) from the T-X phase diagram, and to be 67.93/32.07(molar fraction) from the H-X phase diagram, respectively. The eutectic temperature is measured to be 95.7 ℃ by PDSC.