OBJECTIVE： To study the feasibility of overflow dissolution method for evaluating the drug in vitro sustained release performance. METHODS： Overflow dissolution method was established by simulating the drugs elimination in vivo. Using Nifedipine sustained-elease tablets （Ⅰ） from 2 different manufacturers as model drug A， B， concentration-time curve， cumulative release rate- time curve， release velocity-time curve of model drugs in release pool at 3 different overflow speed （0， 1.50， 3.00  mL/min） were investigated. RESULTS： When overflow speed was 0， the cumulative dissolution was consistent with that of the conventional dissolution method. As the overflow speed increased， cmax  of drug A， B was decreased [A： （8.89±0.20）， （5.21±0.04）， （3.51±0.03） μg/mL； B： （7.62±0.05）， （4.80±0.09）， （2.89±0.04） μg/mL]； cumulative release rate was increased [A： （85.47±2.45）％， （94.29±2.44）％， （96.04±2.56）％； B： （73.28±1.13）％， （78.46±1.94）％， （82.50±1.69）％] ； tmax was ahead （A： 1.5， 1.0， 0.5 h； B： 2.0， 1.0， 0.5 h）. CONCLUSIONS： Overflow dissolution method has avoided the inhibition of too large drug concentration on drug release， making complete drug release and more accurate evaluation of in vivo sustained release performance of the preparation.