Abstract: Samples of aspirin tablets from five manufacturers and one kind of aspirin powder were chosen in this experiment. Using the relationship between the dissolution rate in vitro and the blood drug level in vivo as indexes, we did the experiment for comparison of these four different methods (cup method, disintegration method, rotating basket method and column type method). The parameter T₅₀ (medium time, 50%), Td (characteristic time, 63.2%), m (slope) and Tmax (peak time), Cmax (Peak concentration) and Auc (area under the curve of blood level and time) were acquired.From the F values there appears to be singnificant differences in all parameters(P<0.01) and the sensitivity of column type method is better than the others, but the coefficient of variation of cup method is smaller There is a correlations of results between the parameter in vitro and the peak time in vivo of column type method.