The dynamic monitor is considerably valuable to thoroughly understand the self-assembly process and is beneficial for the effective control of ordered colloidal crystal. In this study, the three-dimensional ordered colloidal crystals are fabricated through thermally assisted self-assembly, which are in situ monitored by fiber-optic spectrometer and micro-digital technology. The assembly process occurs layer by layer from top to bottom. The evaporated water-dragged microspheres assemble into the final close-packing face-centered cubic arrangement. During self-assembly, water between microspheres is gradually replaced by air, resulting in the change of effective refractive index, as well as evident color change and blue shifting of wavelength peaks. The effect of self-assembly temperature (60, 70, 80, and 90 A degrees C) and polystyrene microspheres concentration (4, 6, 8, and 10 wt%) are both investigated on the basis of dynamic monitoring of the thermally assisted assembly of colloidal crystal structural color. As confirmed, the emulsion of 10% mass fraction self-assembled at 70 A degrees C can obtain a superior color film structure.