目的：优化制备工艺，用可生物降解的成球材料制备缓释并有优良抗生育效果的左炔诺孕酮聚３羟基丁酸酯微球。方法：以均匀设计优化微球的液中干燥法制备工艺，用ＤＴＡ确证含药微球的形成，对微球的外观、粒径、载药量、体外释药、稳定性及小鼠体内抗生育等进行了研究。结果：微球平均粒径为６４μｍ，（２８７～８５８）μｍ的微球占总数９０％以上，微球中氯仿残留量低于０００１％，体外释药符合Ｈｉｇｕｃｈｉ方程，释药Ｔ１／２比原药延长约１８倍，４，２５及４０℃（ＲＨ７５％）放置３个月稳定。对小鼠具有抗生育效果。结论：微球的制备工艺满意，与原药相比，微球对小鼠有明显的缓释、延长抗生育时间和降低毒性的作用 OBJECTIVE: To optimize preparation process and prepare levonorgestrel-poly 3hydroxybutyrate microspheres with sustained release and excellent antibiotic effect by using biodegradable pelletizing material. Methods: The preparation process of liquid microspheres was optimized by uniform design. The formation of drug-containing microspheres was confirmed by DTA. The appearance, particle size, drug loading, in vitro release, stability and in vivo anti- Fertility, etc. were studied. Results: The mean diameter of the microspheres was 64μm. The microspheres (287 ~ 858) μm accounted for more than 90% of the total number of microspheres. The residual chloroform content in the microspheres was less than 0001%. The in vitro release was in accordance with Higuchi equation The drug T1 / 2 is about 1.8 times longer than the original drug, and stable at 4, 25 and 40 ℃ (RH75%) for 3 months. Anti-fertility effects on mice. Conclusion: The preparation process of microspheres is satisfactory. Compared with the original drug, the microspheres have a significant sustained release in mice, prolonging the anti-fertility time and reducing the toxicity