A novel conjugate for rosuvastatin has been prepared by a coupling reaction between rosuvastatin and dextran. The dextran–rosuvastatin conjugates (DRC) were characterized by FT-IR, NMR, and XRD. And the resulting DRC self-assembled into microparticles by controlled slow exchange of solvents applying dialysis. The size and morphology of DRC microparticles could be controlled through the solvents and pH selection. Particles with different shape and size of microspheres, micro-blocks, micro-flakes or three-dimensional network structure were obtained by adjusting the pH from 9.0 to 13.0. Multiple morphologies of nano- or microparticles were collected in different organic solvents. In vitro release studies suggested that these DRC microparticles had a sustained release manner and the release behavior could be controlled by adjusting their morphology.