OBJECTIVE： To prepare Baicalin monolithic osmotic pump tablets and investigate its in vitro drug release behavior. METHODS： Using accumulative release rate as evaluation index， baicalin solid dispersion was prepared to improve solubility， single factor test and orthogonal test were used to optimize preparation technology （the amount of penetrating agent and pore-forming agent， weight gaining of coating film） of monolithic osmotic pump tablets using baicalin solid dispersion as intermediate. Release rate and mechanism of samples prepared by optimized technology were investigated in 3 kinds of release medium （water， 0.1 mol/L HCl， simulated gastric fluid）. RESULTS： The optimal preparation technology was that penetrating agent sodium chloride was 30 mg； pore-forming agent polyethylene glycol 400 was 20％ amount of excipient cellulose acetate； weight gaining of coating film was 2％. RSD of 12 h accumulative release rate was 1.06％ （n＝3） for 3 batches of Baicalin monolithic osmotic pump tablets prepared by optimized technology. 12 h accumulative release rate of them in 3 kinds of medium were similar to each other， being all more than 80％. Release equation was in line with zero-order drug release model （r＝0.998 5）. CONCLUSIONS： Prepared Baicalin monolithic osmotic pump tablets after optimization can release drug at controlled rate.