In　modern　e-commerce,　people　usually　use　CA　(Certificate　Authority)　to　ensure　the　security　of　information　and　the　reliability　of　both　parties＇　identity.　A　CA　system　is　usually　composed　with　a　CA　and　a　number　of　RA　registration　centers.　To　address　the　network　congestion　caused　by　that　too　many　users　simultaneously　access　the　RA　(Register　Authority),　this　paper　uses　queuing　theory　to　solve　network　congestion　problems.　©　2010　IEEE.