NOVELTY - Biomass pyrolysis system comprises a feeding device for introducing feeding material, a pyrolysis device, a separating and cooling device, an air flue gas component and a generating power component, where the pyrolysis device is connected with the feeding device so as to perform pyrolysis on the biomass raw materials; the separating and cooling device is connected with the pyrolysis device so as to receive and separate coke and pyrolysis gas output by the pyrolysis device; the air flue gas component is connected with the separating and cooling device.    USE - Used as a biomass pyrolysis system.    ADVANTAGE - The energy of the biomass pyrolysis gas product is subjected to gradient utilization, and biomass pyrolysis system has self-sufficient energy and low cost.    DETAILED DESCRIPTION - Biomass pyrolysis system comprises a feeding device for introducing feeding material, a pyrolysis device, a separating and cooling device, an air flue gas component and a generating power component, where the pyrolysis device is connected with the feeding device so as to perform pyrolysis on the biomass raw materials; the separating and cooling device is connected with the pyrolysis device so as to receive and separate coke and pyrolysis gas output by the pyrolysis device; the air flue gas component is connected with the separating and cooling device so as to combust the pyrolysis gas and the preheated air and respectively feed the gas back to the feeding device and the pyrolysis device; and the generating power component is connected with the air flue gas component so as to convert the heat of the pyrolysis gas and the preheated air into mechanical energy and supplement the power source of the pyrolysis device and the separating and cooling device. An INDEPENDENT CLAIM is also included for biomass pyrolysis by self-sufficient energy of biomass pyrolysis device, comprising: (i) adding the biomass raw material into feeding device; (ii) passing the biomass raw material containing 2-3% oxygen at 150-250 degrees C under the protection of low-temperature flue gas downstream into the pyrolysis unit, at 500-700 degrees C under high temperature gas carrying out external countercurrent heat, and heating to 400-600 degrees C pyrolysis temperature to form char and tar-containing gaseous products; (iii) cooling the coke by indirect heat exchange with the collected air; (iv) carrying out combustion reaction of air after heat exchange with the pyrolysis gas to form a high temperature flue gas; and (v) passing the high temperature flue gas into first flue gas channel and second flue gas channel, and respectively cooling in high-temperature heat exchanger to 500-700 degrees C and 150-250 degrees C, where the flue gas from the first channel and the second channel are returned to step (ii).    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the biomass pyrolysis system.