Research on optical coherence tomography (OCT) applied in pearl identification and nacre measurement is represented. Due to the difference of scattering properties for various components, OCT image characteristics can exact the two-dimensional information of subsurface structure of pearls, which could only be previously accomplished by the conventional section. An OCT system mainly composed of fiber Michelson interferometer with wideband source of 1310 nm central wavelength and Fourier-domain optical delay line has been implemented. The system can complete the nondestructive and real time detection, with scanning speed of 1 frame/s, depth resolution of 15 μm and penetration depth of 3 mm. Experimental results included determining the structural identity: nacreous layer or shell nucleus, quantifying the nacre thickness (measuring errors less than 20 μm), and showing abnormal information of shell-nucleous features.