Abstract: OBJECTIVE To investigate the preparing methods and process of 9-nitrocamptothecin (9-NC) stealth liposomes composed of HSPC and SPC and to compare the pharmaceutical properties between 9-NC liposomes and 9-NC stealth liposomes. METHODS Encapsulation efficiency determination method for 9-NC stealth liposomes was established by ultrafiltration membrane method. The preparation for 9-NC stealth stealth liposomes was carefully studied and the process parameters were optimized. Furthermore， compared with 9-NC liposomes composed of HSPC and SPC without stealth-modified， encapsulation efficiency， particle size， zeta potential and polydispersity lactone stability were investigated. RESULTS The encapsulation efficiency of 9-NC stealth liposomes preparation by film-ultrasonic method was significantly improved， compared to those by ethanol injection method， and the optimized process parameters were HSPC:SPC=1:9. The formation time was 100min and formation pressure was 0.095 Mpa. Though there was on influence on the exception of encapsulation efficiency （80%） and zeta potential， particle size and lactone stability were significantly optimized by modified stealth materials. CONCLUSION Samples prepared by optimized method and process obtained high encapsulation efficiency and met the needs of drug effects in vivo studies; modified stealth materials may have effect in enhancing Lactone stability of 9-NC stealth liposomes composed of HSPC and SPC.