Object To investigate the preparation technique and optimal formulation of Breviscapin Sustained release Pellets (BSP) and the release mechanism of breviscapin from the pellets. Methods BSP was prepared by extrusion spheronization method. Based on the studies of influential factors, optimal formulation modified to release drug over 12 h was obtained by the orthogonal design. And release mechanism of breviscapin from BSP was established by equation fitting. Results Prepared BSP has such advantages as simple technique, uniformity in diameters and high loading with even contents. They can release drug for 12 h. And the release of breviscapin could be mainly controlled by diffusion associated with slight erosion. Conclusion Extrusion spheronization method is simple for the preparation of BSP, and useful for the large scale prodution.