Background：Intrauterine device（IUD）is one of the most popular method of longacting contraception，while concerns still exist as to whether the use of IUD increases the risk of pelvic inflammatory disease（PID）. In recent years many issues have been extensively researched about the relationship between bacterial biofilm（BF）and infectious diseases. We designed this study to investigate whether BF exists on IUD of non PID women ；and whether IUD increases the susceptibility to PID. Methods：For the study，we recruited 85 participants without PID and a PID patient who choosed IUD as a means of contraception. According to the cleanliness of IUD surface.IUD was removed and sent for scanning electron microscopy（SEM） or/and biological and fungal examination respectively to detect BF. Results：A total of 86 IUDs were recruited ，which include stainless steel ring，TCuIUD，Mirena，Multiload，McuIUD and γCu380 IUD. Among 25 IUDs which were observed with SEM alone，BF was discovered on a TCuIUD used for one month-a large number of bacilli /cocci and extracellular matrix coverd on the surface of copper. Other specimens had no significant discoveries. The result of 47 microbial culture alone was negative except for one suspected contaminated IUD. 14 IUDS were investigated via both microbial culture and SEM. A 33 year old stainless steel ring which removed because of the symptoms of pelvic pain，aerobic cultivation was positive.But there was no BF detected by SEM.The remaining 13 IUD had no positive result.Conclusions：There was no BF on surface of IUD removed from non- PID women regardless of IUD type；unlike other medical device，the formation of bacterial biofilm should not become a stumbling.