Objective: To study the formulation and technol. of isosorbide mononitrate capsules.Method: Use an extrusion spheronizer to prepare isosorbide mononitrate-containing pellet cores, use a coating machine for slow-release coating, and fill the pellet cores into hollow capsule shells.The in vitro release rate of sustained-release capsules was determined, and the effects of pellet core preparation parameters, coating materials and coating weight gain on the release rate were investigated.Results: Et cellulose was selected as the slow-release coating material, and the coating weight gain 8% had the best release effect.The best pellet preparation conditions were selected: extrusion speed 15r · min-1, spheronization time 5 min, spheronization speed400 r·min-1.Under the optimal conditions, the release effect of sustained-release capsules has good inter-batch reproducibility.Conclusion: Under the conditions of this prescription, the process of isosorbide mononitrate sustained-release capsules is simple and feasible, with good reproducibility, and achieves a better sustained-release effect.