To investigate the feasible application of the bioassay method in the evaluation of traditional Chinese medicine sustained-release preparations, develop a rapid drug-release evaluation method in vitro for multi-component preparations, and replace the biological activity determination method characterizing the overall behavior with the existing drug-release evaluation method for single component, in order to give better instruction for sustained-release preparations. HPLC was adopted to determine dissolution media, drug releasing rates, and accumulative releasing of active ingredients (salvianolic acid B, protocatechuic aldehyde and rosmarinic acid) of Salvia Miltiorrhiza hydrophilic gel matrix tablets. The ultraviolet spectroscopy was adopted to determine the antioxidant activity of release media, and evaluate the correlation between the drug-time curve of various drug components and the drug-time curve of the total antioxidant activity. The correlation coefficient between the drug-release curve of various components and the drug-time curve of the total antioxidant activity was higher than the critical value r 0.898 (P < 0.001). This indicated that the drug-release curve of the three phenolic acids and the drug-time curve of the total antioxidant activity had a good correlation in different conditions, such as dissolution media, release rates and component ratios. The bioassay method for determination was feasible, simple and convenient for preparation quality evaluation and prescription design in the place of in vitro dissolution.