Abstract: Abstract Aim： To develop marine microporous osmotic pump tablets and to investigate drug release in vitro of the optimized formulation and the release mechanism. Methods： Wet granulation and film-coating were used to develop marine micro-osmotic pump tablets. in vitro release studies were applied to evaluate the impacts of various factors on the release of the formulation.Central-composite design was exploited to aid the optimization of the formulation，and the mechanism of in vitro release was characterized. Results： There existed fairly good reproducibility in the preparation of marine micro-osmotic pump tablets.It was found that no change in the release rate of the tablets were elicited by the pH of the release media，the rotating speed selected，the hardness of the tablet core，and the amount of the plasticizer incorporated into the coating formulation.It was proved that the release of marine micro-osmotic pump tablets was closely related to the magnitudes of NaCl amount in the tablet core and the pore former in the coating formulation as well as the coating level.In addition，there existed 12-hr zero-order kinetics in the in vitro release study of the tablets.Moreover，it was shown that the osmotic pressure-controlled delivery is greatly responsible for the release of the developed tablets. Conclusion： The prepared marine microporous osmotic pump tablets are expected to be a new sustained-release medication.