The thermodynamic data of heat flow curve, heat transfer coefficient and heat capacity in nitration reaction of 2-methylpyrimidine-4, 6-dione in the synthesis of 1, 1-diamino-2, 2-dinitro ethylene(FOX-7) were measured by using reaction calorimeter(RCle). Results show that the average heat release rate of nitration reaction in feeding is about 80W and in the finishing period about 40W. The total exothermic heat of nitration reaction is 375.22 kJ·mol^-1, and the adiabatic temperature rise is 483.8 K. The thermal behaviors of 2-dinitromethylene-5, 5-dinitropyrimidine-4, 6-dione were analyzed by differential scanning calorimeter and thermogravimetry-derivative thermogravimetric analysis techniques. Results show that its thermal decomposition process can be divided into two stages. The initial decomposition temperature is 30 ℃, the peak temperature of first-stage is 67.01 ℃ and the enthalpy of decomposition reaction is 201.2 J·g^-1. The peak temperature of second-stage is 87.15 ℃ and the enthalpy of decomposition reaction is 1046.6 J·g^-1. This indicates that the thermal stability of 2-dinitromethylene-5, 5-dinitropyrimidine-4, 6-dione is bad.