Abstract: OBJECTIVE To prepare nimodipine chitosan microsperes, and investigate their release characteristics in vitro. METHODS Chitosan was used as a carrier, liquid paraffin as oil phase, glutaradehyde as the cross-linker, and Span-80 as emulsifier. Nimodipine chitosan microspheres was prepared using emulsion-linking technique, in which orthogonal experimental design was introduced to optimize the preparation conditions. The release characteristics of the microspheres was investigated in artificial gut fluid in vitro. RESULTS After optimizing, the microspheres with good shape, smooth surface and narrow size distribution were prepared. The average particle size was 9.56 μm, the drug loading rate was 17.82% and the entrapment rate was 52%. The release rate of the microsperes could be appropriately simulated by first order kinetics equation. CONCLUSION The preparation procedure established was stable and practical, and the microspheres obtained showed good sustained release characteristics.