Abstract Doped carbon dots (CD) exhibit novel luminescence properties that was commonly used as fluorescence probesinnanoanalysis. The another excellent property of catalysis was also interesting to analysts to amplify signal in spectral assay. In this article, highly catalysis N,Au co-doped carbon dots (CDN/Au) were quickly fabricated by microwave irradiation, using corn starch, ethylenediamineand chloroauric acid as precursors. Some preparedCDs were characterized in details by molecular spectroscopy, diffraction of X-ray (XRD) and Michaelis constant. The CDN/Aushowedpowerful catalysis in the fluorescence/absorption indicator reaction of H2O2-3,3′,5,5′-tetramethylbenzidine (TMB) to from oxidized productTMBOXwith fluorescencepeak at 403 nm and absorption peak at 563 nm. The nanoenzyme reaction was coupled with the DNAzyme reaction of K+-aptamer(Apt)-hemin (HM), a new dienzymecatalytic fluorescence/absorption di-modemethod for ultratrace K+ was developed. In addition, the analytical principle and the dienzyme co-catalysis mechanism were studied.