A composite slurry containing yellow phosphorus and phosphate slurry was used to remove NOx from flue gas, where yellow phosphorus is considered to promote generation of ozone from oxygen. The latter can oxidize NO to form more water-soluble NxOy species, finally converted to HNO2 and HNO3. These acids can react with phosphate slurry to form PO43-. Thus, the final solution containing NO3- and PO43- can be potentially used as raw material for the production of nitrogen phosphorus compound fertilizer. Moreover, effects of various parameters on NOx removal efficiency were optimized, and single factor experiments together with response surface optimization were applied for optimizing these parameters. It was indicated that the removal efficiency of NOx can obtain 99.2% under optimal conditions. Subsequently, the corresponding reaction mechanisms were discussed. Therefore, using the mixtures of yellow phosphorus and phosphate slurry as absorbent not only obtains high NOx removal efficiency, but can avoid the need to dispose of spent liquid wastes, which provides an attractive approach for controlling NOx. Moreover, the present slurry system can eliminate NOx and SO2 simultaneously with high removal efficiency.