In neutral medium, berberine forms a red-violet association microparticle with PHLO which has an maximum absorption at 560 nm, Beer's law is obeyed for berberine in the concentration range of 6.65 x 10(-7)-7.71 x 10(-5) mol x L(-1). Spectral properties of the berberine-PHLO system were studied. In neutral medium, there are a maximum absorption peak at 520 nm and a fluorescence peak at 560 nm for PHLO. Berberine and PHLO combine into a hydrophobic berberine-PHLO association molecule by static gravitation. With stronger Van der Waals and hydrophobic forces among berberine-PHLO molecules, it forms association particle in red-violet which exhibits three resonance scattering peaks at 385, 470 and 586 nm, respectively. The fluorescence quenching at 560 nm is because the PHLO molecule in the body of the particle may not be excited by incident photons, so it does not emit fluorescence.