The captopril/Chitosan gelatin net-polymer microspheres ( Cap/CGNPMs) were prepared using Chitosan ( CS) and gelatin ( Gel) by the methods of emulsification. A cross linked reagent alone or in combination with microcrystalline cellulose (MCC) was added in the process of preparation of microspheres to eliminate dose dumping and burst phenomenon of microspheres for the improvement of the therapeutic efficiency and the decrease of the side effects of captopril ( Cap) . The results indicate that CapPCGNPMs have a spherical shape , smooth surface morphology and integral inside structure and no adhesive phenomena and good mobility , and the size distribution is mainly f rom 220 to 280 μm. Researches on the Cap release test in vitro demonstrate that Cap/CGNPMs are of the role of retarding release of Cap compared with Cap ordinary tablets ( COT) , embedding ratio ( ER) , drug loading ( DL) , and swelling ratio ( SR) , and release behaviors of CGNPMS are influenced by process conditions of preparation such as experimental material ratio ( EMR) , composition of cross linking reagents. Among these factors , the EMR (1/4) , CLR ( FOR + TPP) and 0. 75 % microcrystalline cellulose (MCC) added to the microspheres are the optimal scheme to the preparation of Cap/CGNPMs. The Cap/CGNPMs have a good characteristic of sustained release of drug , and the process of emulsification and cross-linking process is simple and stable. The CGNPMs is probable to be one of an ideal sustained release system for water-soluble drugs.