In order to establish a precise combustion heat measurement system and method suitable for energetic materials， a method and device for measuring the heat of combustion of energetic materials with tiny doses has been developed. This device is based on the thermal principle of differential heat flux and uses a three-dimensional thermopile consisting of 960 pairs of thermocouples as the core measuring element. The device was calibrated by using standard material benzoic acid. The heat of combustion of six typical energetic materials， including cyclotetramethylene tetranitramine， hexanitrohexaazaisowurtzitane， cyclotrimethylene trinitramine， 3，4-bis（3-nitrofurazan-4-yl）furoxan， 1，1-diamino-2，2-dinitroethylene and nitroguanidine， was measured by this device. The results show that the calorimetric coefficient of the instrument is （64.804±0.071） μV·mW^-1 and the corresponding relative uncertainty is 0.109%. The solid-phase standard molar heats of combustion （Δ_cU） of these six energetic materials at 298.15 K are -（2749.1±4.5）， -（3593.6±6.0）， -（2115.2±3.4）， -（3040.8±4.8）， -（1211.4±2.3） and -（898.4±2.0） kJ·mol^-1， respectively. The measurement results are in good agreement with the values reported in the literature， indicating that the developed small-mass combustion measurement device can be widely used in the determination of the energy of combustion of substances containing C， H， O， and N， especially precious samples and explosive substances.