The utility model relates to a third-stage cyclone separator with a high treating capacity, which is a device that is used on the energy-recovering system of an oil-refining catalytic cracker to conduct gas-solid separation. The cyclone separator comprises a shell, a fume outlet, a fume inlet, a central pipe, a plurality of self-contained cyclone separators, a hung partition plate, etc.; wherein, the interior of the shell is divided into three relatively independent spaces, an inlet chamber, a collection chamber and a dust collection chamber; and the self-contained cyclone separators which are arranged into inner and outer rings and upper and lower layers are assembled in the shell. The arrangement can ensure that the cyclone separators can maintain the optimal pressure balance and uniform airflow distribution, thus ensuring the operation stability and long-period safe operation of the cracker; the arrangement also ensures that the smallest space of planes and vertical planes can contain as many high-treating-capacity, high-performance swirl separators as possible, resolves load and thermal expansion problems, and reduces equipment investment.