Abstract: The sustained-release pellets of metoprolol succinate which comprise a drug-layered sugar core and a ethyl cellulose layer were prepared by a fluid bed dryer. The release of the domestic products and the commercial ones were tested in pH 6. 8 PBS, 0. 1 mol/L HCl and water based on the USP standard. And f₂ value was calculated. In vivo pharmacokinetic parameters of self and domestic products were also compared. The results showed that the formula could reach the USP standard and the optimal ratio of sugar core(200-300 μm in diameter), drug layer and EC layer based on the sugar core weight was 100: 100: 45. 4-50. 92. The f₂ value of the release curves in pH 6. 8 PBS, water and 0. 1 mol/l HCl was 79. 34, 65. 04, 54. 43, respectively. Analysis of variance indicated no significant deviation between the two products.