Abstract: OBJECTIVE To prepare sodium houttuy sustained-release tables (SH-SRTs) and to investigate its in vitro release mechanism. METHODS SH-SRTs were prepared by employing HPMC, the mixture of HPMC and EC as matrix materials, and its in vitro release profiles were evaluated by accumulative release percentage. RESULTS The viscosity of HPMC, the contents of HPMC and EC influenced significantly the release of drug, but the different diluents had few effects on drug release. The release of SH-SRTs was fitted with the Higuchi equation. CONCLUSION SH-SRTs indicate a sustained release profiles, and the drug release pattern of the sustained tablets is non-Fick diffusion mechanism.