Objective:To prepare an X-ray developable alginate-barium sulfate microspheres as material for embolic agent.Methods: The emulsification-internal gelation technique was used to prepare alginate microspheres and the orthogonal design was adopted to optimize the technique.The diameter,shape,dispersibility,stability,suspension property,coating ratio and developability under X-ray of the microspheres were examined.Results: The average diameter of the microspheres was (53.08±32.72) μm; they were well distributed and had a round shape.The ratio of the destroyed microspheres was (2.0±1.1)% after heated at 100℃for 2 h,(86.0±19.2)% after frozen at -4℃ for 24 h,(39.0±14.7)% after vibrated at 37℃ for 24 h,and (10.3±3.2)% after irradiated with 60Co(10kGy)for 0.5 h.The ratio of sedimentation volume in 0.25% suspension of sodium alginate microspheres was (0.92±0.018).The coating rate was (69.2±13.2)% when the feeding amount of barium sulfate was 2.0 g,and the result of X-ray development was good.Conclusion: Alginate-chitosan can be used for the preparation of barium sulfate microspheres; and the emulsification-internal gelation technique can prepare the microspheres with good dispersibility and shape.