The aim is to determine the optimum preparation technol. of mitiglinide calcium hydrate sustained-release tablets and investigate the release rate in vitro. The single factor investigation and orthogonal test design were used to determine the optimum preparation technol. of mitiglinide calcium hydrate sustained-release tablets, and determine the release rate in vitro according to the Chinese Pharmacopoeia of 2010 edition. (volume II). The formula of mitiglinide calcium hydrate sustained-release tablets comprised mitiglinide calcium(5.0g), HPMC(K15M, 30.0g), lactose (80.0g), 3% PVP water solution (appropriate amount) and magnesium stearate (2.0g). The optimum preparation technol. was as follows: putting the above-mentioned raw materials through 120 mesh sieve, fully drying, weighing according to the formula and mixing, making a soft material as a binder using 3% PVP water solution, granulating with 40 mesh sieve and drying at 50°C, processing granule with 40 mesh sieve, adding lubricant and blending, and determining the content, stamping with shallow circular arc(φ7 mm) at a pressure 8 kg/cm2 to make each piece at a weight of 120mg. The release profile in vitro of mitiglinide calcium hydrate sustained-release tablets conformed to Higuchi equation(r=0.9983). The release rate of mitiglinide calcium hydrate sustained-release tablets prepared in this study has a good sustained release effect.