Heat of reaction(s) during transfer fast pyrolysis of biomass powder was investigated by the equipment of differential scanning calorimetry (DSC). The Cellulose or Lignin or Xylan powder was set into the aluminum pan in the equipment. For Cellulose powder, DSC decreased with the temperature in the aluminum pan, T, due to evaporation of water and emission of some volatile matter content at 327 K < T < 462 K. Endothermic and exothermic signals were observed at 560 K < T < 607 K and at 607 K < T < 638 K, respectively. For Lignin powder has two endothermic peaks at 491 K < T < 495 K and 503 K < T < 549 K while the exothermic signal was observed at 549 K < T < 682 K. Xylan powder, endothermic and exothermic signals were observed at 371 K < T < 477 K and at 477 K < T < 602 K, respectively. These results agreed qualitatively with our previous experiments. Furthermore, the heats of reactions were estimated by using DSC curves for all powders.