Amorphous photonic crystals PDA/SiO2 (APCs) in three different colors, blue, green and red, were prepared by coating SiO2 microspheres with polydopamine (PDA) using a modified St?ber method with three particle sizes of 187, 245 and 274 nm; the amorphous photonic crystals PDA/SiO2 were introduced into polyurethane (PU) to produce the composite material PDA/SiO2/PU. The structure and properties of PDA/SiO2 and the composite PDA/SiO2/PU were characterised using FT-IR, CA, SEM, TEM, UV-Vis, DLS, and a universal testing machine. The results show that the color of the APCs depends on the particle size of the SiO2 microspheres; the color saturation of the APCs can be adjusted by adjusting the amount of PDA coating; the introduction of the APCs into the PU results in a dark red structured polyurethane with a maximum tensile strength of 40.28 MPa and a water contact angle of 113°, which gives the polyurethane structural chromogenic and excellent mechanical properties and hydrophobicity.