Abstract: Single event multiple upset (SEMU) experimental results of high-density static random access memory (SRAM) are presented.The devices un der tests (DUTs) were bombarded by heavy ions from HI-13 tandem accelerator an d h eavy ion research facility in Lanzhou (HIRFL).A high-resolution tester for sing le event upset (SEU) in SRAMs,which is based on network communication protocol, was utilized to detect SEMUs occurred.Experimental results show that different me chanics can cause SEMU,SMU in HM628128ALP and HM628512LP were due to diffusing o f changes created by single ion to neghbouring junction.It was confirmed that sin gle event transients (SET) occured in peri-pheral circuit could cause SMU a nd pro ducts of spallation reactions of incident heavy ions with encapsulation material s also could contribute to SEMUs in case of glancing incidence.SMU rates of Hita chi SRAMs in geosychronous orbit and two sunsychronous obits were predicted. Subject Term Static storage Radiation effect Multiple bit u pset Experimentation