Abstract: OBJECTIVE To study the form of Venenum Bufonis sustained-release pellets and its release mechanism in vitro. METHODS Venenum Bufonis sustained-release pellets were prepared by extrusion-spheronization method. Using the X-ray powder diffraction method to study drug compatibility with powder of compatibility. Preparation surface microscopic was observed by a scanning electron microscope method. Release mechanism of Venenum Bufonis sustained-release pellets was established by equation fitting. RESULTS Excipient had no obvious effect on the existence form of extracts of Venenum Bufonis. with the increase of dissolution time, coating film of Venenum Bufonis sustained-release pellets desaturationed and multiple damaged. Drug release curve conformed to Higuchi equation. CONCLUSION The Venenum Bufonis sustained-release pellets show good sustained-release effect.