A method for preparing the sustained release formulation as claimed in claim 1, comprising the steps of mixing the HMG-CoA reductase inhibitor, the solubilizing agent, and the stabilizing agent in a solvent selected from water, ethanol and methylene chloride to obtain the solid dispersant homogeneously mixing the mixture of sodium alginate and xanthan gum as the sustained release composite carrier and the mixture of propylene glycol ester alginate and hydroxypropyl methyl cellulose as the gel hydration accelerator with the solid dispersant to form a first mixture adding a pharmaceutically acceptable additive to the first mixture to form a second mixture "and dry-mixing and formulating the second mixture into the sustained release formulation, wherein the solubilizing agent is selected from the group consisting of d-a-tocopheryl polyethylene glycol 1000 succinate, polyoxyethylene stearic acid ester, polyethylene glycol and polyoxypropylene-polyoxypropylene block copolymer, the stabilizing agent is selected from the group consisting of butylated hydroxy toluene, butylated hydroxy anisol, erythorbic acid and ascorbic acid, the pharmaceutically acceptable additive is selected from the group consisting of binder, lubricating agent, sweetening agent and excipient, the solubilizing agent is 0.05 to 20 weight part the stabilizing agent is 0.01 to 0.1 weight part the sustained release composite carrier is 3 to 30 weight part and the gel hydration accelerator is 0.1 to 5 weight part based on 1 weight part of the HMG-CoA reductase inhibitor.
