A real-time online analysis device for substance pyrolysis, characterized in that, the device comprises: a pyrolyzing system, a capturing system, a testing system and a controlling system; wherein: the pyrolyzing system, the capturing system and the testing system are connected with the controlling system; the capturing system has a cooling cavity and a heating cavity inside, temperature of the cooling cavity ranges from room temperature to -200°C, and temperature of the heating cavity ranges from room temperature to 1000°C; and wherein the capturing system comprises the following components: A horizontal moving slot; A cooling cavity, arranged at one end of the horizontal moving slot; The cooling cavity has a cooling tube, which is connected with a cooling gas device; the cooling cavity is in airtight connection with the pyrolyzing system through a gas pipeline; A heating cavity, arranged at the other end of the horizontal moving slot; the heating cavity has a heating tube; the heating cavity is in airtight connection with the testing system through the gas pipeline; A rotary collector arranged on a horizontal moving slot between the cooling cavity and the heating cavity, which can slide along the horizontal moving slot towards the cooling cavity or the heating cavity; a plurality of collecting tubes are provided on a rotary collector, and the plurality of collecting tubes are arranged on the radius of the rotary collector; A purging gas pipe connected to the rotary collector. the pyrolyzing system, the capturing system and the testing system are connected with the controlling system; the capturing system has a cooling cavity and a heating cavity inside, temperature of the cooling cavity ranges from room temperature to -200°C, and temperature of the heating cavity ranges from room temperature to 1000°C; and wherein the capturing system comprises the following components: A horizontal moving slot; A cooling cavity, arranged at one end of the horizontal moving slot; A horizontal moving slot; A cooling cavity, arranged at one end of the horizontal moving slot; The cooling cavity has a cooling tube, which is connected with a cooling gas device; the cooling cavity is in airtight connection with the pyrolyzing system through a gas pipeline; A heating cavity, arranged at the other end of the horizontal moving slot; the heating cavity has a heating tube; the heating cavity is in airtight connection with the testing system through the gas pipeline; A rotary collector arranged on a horizontal moving slot between the cooling cavity and the heating cavity, which can slide along the horizontal moving slot towards the cooling cavity or the heating cavity; a plurality of collecting tubes are provided on a rotary collector, and the plurality of collecting tubes are arranged on the radius of the rotary collector; A heating cavity, arranged at the other end of the horizontal moving slot; the heating cavity has a heating tube; the heating cavity is in airtight connection with the testing system through the gas pipeline; A rotary collector arranged on a horizontal moving slot between the cooling cavity and the heating cavity, which can slide along the horizontal moving slot towards the cooling cavity or the heating cavity; a plurality of collecting tubes are provided on a rotary collector, and the plurality of collecting tubes are arranged on the radius of the rotary collector; A purging gas pipe connected to the rotary collector.