Combined rotary kiln incineration system capable of sufficiently incinerating slag

The utility model discloses a combined rotary kiln incineration system capable of sufficiently burning slag. The combined rotary kiln incineration system comprises a rotary kiln, a vertical slag burning chamber, a rotary fire grate, a slag discharging device and a secondary combustion chamber, wherein a feeding hole is formed in the front end of the rotary kiln, and the kiln tail of the rotary kiln is connected with an inlet in the upper end of the vertical slag burning chamber; a rotary fire grate is arranged at the bottom of the vertical slag burning chamber, a slag discharging opening is formed below the rotary fire grate, and a slag discharging device is arranged below the slag discharging opening; a flue gas outlet is formed in the side wall of the upper portion of the vertical slag burning chamber and connected with a secondary combustion chamber, and a high-temperature flue gas outlet is formed in the top of the secondary combustion chamber. A combustion-supporting air inlet isformed below the side sur