The invention belongs to the technical field of pyrolysis and cracking of fossil fuel and in particular relates to a self-dust-removal type pyrolysis and catalytic cracking reactor which is mainly specific to resources such as oil shale and coal and used for preparing flammable gas and semicoke products. The invention, aiming at overcoming the defects of the prior art, designs and develops a self-dust-removal-type pyrolysis and catalytic cracking reactor. In the reactor, a pyrolysis chamber and a cracking chamber are designed in an integrated manner, oil gas produced in the pyrolysis chamber enters a particle bed dust removal device, after dust removal is carried out by the particle bed dust removal device, clean oil gas enters the cracking chamber to be deeply cracked, rear-end dust removal pressure is reduced, macromolecular tar molecular is cracked into micromolecular gaseous hydrocarbon, and a large amount of hydrogen is produced in a catalytic cracking manner, so that the problem that pyrolyzed oil contains dust is avoided and clean and efficient utilization of the fossil fuel is really realized.