The micronization of emodin in a mixed solution of dichloromethane and methanol by the Solution Enhanced Dispersion by Supercritical Fluids through Prefilming Atomization (SEDS-PA) process has been successfully performed. Morphologies and particle sizes (PSs) of the emodin microparticles were analyzed by scanning electron microscopy. The results of micronization show that the acicular or rod-like emodin crystals with PSs of about 3-10 µm wide and 100-300 µm long have successfully been micronized to needle-like, rod-like, twisted fiber-like and coalesced net-like microparticles with PSs of about 0.1-1.0 µm wide and 2-40 µm long by the SEDS-PA process. The effect of technological conditions on micronization has been studied. With the increase of initial solution concentration and temperature, the PSs of emodin microparticles increase. With the increase of solution flow rate and pressure, the PSs of emodin microparticles decrease.