A dry low NOX staged combustion system includes a fuel nozzle and a combustion compartment. The fuel nozzle includes a purge gas tube, a diffusion combustion fuel tube, an isolation gas tube, a premixed combustion fuel tube, a premixed combustion air tube. The purge gas tube is configured to feed a purge gas. The diffusion combustion fuel tube is fitted over the purge gas tube, and having an end provided with a diffusion combustion fuel swirler. The isolation gas tube is fitted over the diffusion combustion fuel tube. The premixed combustion fuel tube is fitted over the isolation gas tube. The premixed combustion air tube is fitted over the premixed combustion fuel tube. The combustion compartment is located downstream of the fuel nozzle.