The influence of ammonium ion in fly ash on cement performance was studied by adding ammonium sulfate into fly ash to simulate fly ash with different ammonium ion content. The test shows that the influence of fly ash ammonium ions on the standard consistency of different varieties of cement should be confirmed through the actual production; the condensation time of cement can be extended after the fly ash ammonium ion content reaches a certain value; when the fly ash ammonium ion content is 500~2 000 mg/kg, the compressive strength of cement 3d and 28d is significantly reduced; when fly ash with 30% ammonium content of 2 000 mg/kg was added to P·I52.5 cement, fly ash ammonium ions had little effect on the adaptability of cement and aliphatic superplasticizers, but had a certain impact on the adaptability of cement and polycarboxylic acid superplasticizers.