Abstract: This paper presents a biologically-motivated algorithm for flower color pattern simulation.Cooperated with reaction-diffusion system and spectral representation of color,our algorithm combines pigment distribution simulation and pigment color expression together under a unified framework.By the method, we first simulate the pigment distribution with a modified reaction-diffusion system,which is integrated with venation information.Then,unlike traditional painting or photo-based method,pigments absorption spectra are substituted into the diffuse lighting model to obtain the reflectance data.More importantly,our system is highly controllable and can be adjusted to produce various flower color patterns widely observed in the real world.Furthermore,our algorithm can be easily embedded into other advanced shading models to improve the reality of their final results.