Abstract: Nacre’s iridescence results from the interaction of visible light and the nacre’s microstructure.In this study，using the scanning electron microscope（SEM）to observe the nacre’s structure in the abalone shells and a portable fiber optic spectrometer to measure the corresponding reflectance spectrum of nacre，the results show that the thickness of aragonite platelets varies from different regions of nacre，499±35nm at the shell edge and 371±36nm at the shell center，which causes obvious variation of nacre’s iridescence.What’s more，the structural colour of nacre at the shell edge is the secondary colour of blue and yellow，whereas the one at the shell center is the secondary colour of blue and red.Additionally，the authors measured the multiple reflectance spectra for the first time and applied a quantitative model to analyze the nacre’s iridescence in abalone shells.