As a novel amide local anesthetic, ropivacaine (ROP) is widely used in postoperative pain management. However, ROP has a short half-life (t1/2=1.8 h), and multiple doses in clinical is needed to meet the demand for analgesia, resulting in poor patient compliance. In this study, ROP-PLGA microspheres were prepared by using the premix membrane emulsification technique combined with the double emulsion-solvent evaporation method. Finally, the uniform microspheres with particle size of 7.831 μm and Span value of 0.874 were prepared under 1.5% (w/v) of PVA in external aqueous phase, 1:7.5 of volume ratio of oil phase-external aqueous phase (O/W2), 300 r/min of stirring rate of pre-double emulsion as well as 10 kPa of trans-membrane pressure. Additionally, factors such as the pH of external water phase, PLGA concentration in oil phase and internal water phaseoil phase volume ratios (W1/O) on the effect of encapsulation efficiency (EE) and the drug loading (DL) were investigated based on response surface method (RSM). The optimal formulation and process parameters designed by RSM were as follow: the pH of the external water phase was 11, PLGA concentration in oil phase was 15%(w/v), internal water phaseoil phase volume ratios (W1/O) were 1:10. Moreover, the model predicted the DL of 17.6 μg/mg and the EE of 53.89% were predicted by RSM model. In the meanwhile, repeatability test showed that the DL was (18.0±0.5) μg/mg and the EE was (55.7±2.69)%. Eventually, the relative error was insignificant (less than 7%), which meant the model was reliable. In vitro release profile showed that the cumulative release of ropivacaine loaded microspheres at three and five days was about 50% and 70% respectively, which indicated that the prepared ROP-PLGA microspheres had a stable sustained release effect and microsphere bioformulation had great potential in the field of sustained release of local anesthetics.