The invention discloses an energy-saving biomass processing pretreatment device. The energy-saving biomass processing pretreatment device comprises a pedestal and a box body. The box body is fixedly installed on the pedestal. A partition plate is fixedly installed inside the box body. A main rotating shaft is installed at the middle position of the partition plate in a rotating mode. Four auxiliary rotating shafts are symmetrically installed on the partition plate in a rotating mode and further located on the periphery of the main rotating shaft. A plurality of first crushing blades are evenlyinstalled at the upper end of the main rotating shaft and the upper ends of the auxiliary rotating shafts at equal intervals. A plurality of second crushing blades are further evenly installed at thelower end of the main rotating shaft and the lower ends of the auxiliary rotating shafts at equal intervals. Two exhaust pipes are symmetrically and fixedly installed on the left side and the right side of the upper portion of the box body. Two preheating pipes are further symmetrically and fixedly installed on the left side and the right side of the upper portion of the box body. The exhaust ends of the exhaust pipes communicate with the insides of the corresponding preheating pipes. According to the energy-saving biomass processing pretreatment device, biomass raw materials are processed into fine particles, so that subsequent processing is facilitated; and the exhaust pipes and the preheating pipes are further arranged to preheat inlet air, energy is recycled, and therefore heat energyis saved, economic benefits of enterprises are increased, and environmental protection can be facilitated.