Nox emission is required to be less than 50 Mg/Nm3 for cement industry according to the environmental policies in some provinces. As Nox can be chemically reduced to N₂ by reduction reaction, this paper will introduce a new method by the combination of two reduction reaction to reduce the Nox emission in cement plant. One reduction reaction is reducing the Nox by CO which is produced in the extended gasifier calciner. Another reduction reaction is reducing the Nox by ammonia which is produced by spraying the ammonia water in the pre-calciner outlet where temperature is between 850°C and 950°C which is considered as the best reaction temperature range for this reduction reaction. Also, the intelligent SNCR system is introduced in the reduction reaction to control the reaction amount of the ammonia water. The intelligent SNCR system can forecast the working situation by studying the clinker calcining system process data. In this way, Both the Nox emission and the ammonia consumption can be substantially reduced.