By　providing　more　information　about　traffic　network,　such　as　more　feasible　paths　via　intelligent　navigation　systems　(INS),　users　in　the　network　may　change　their　choices　of　the　path　from　a　source　to　a　destination.　This　paper　investigates　a　traffic　congestion　model　with　incomplete　information,　in　which　different　users　have　different　information　about　the　network.　We　introduce　the　notions　of　user　equilibrium　of　incomplete　information　(UEII)　and　system　optimum　of　incomplete　information　(SOII).　Then,　we　prove　a　theorem　about　the　effect　of　the　change　of　traffic　amount　on　each　couple　paths　in　SOII　for　the　model.　Finally,　based　on　this　theorem　and　a　property　of　UEII,　we　reveal　a　relationship　between　UEII　and　SOII　on　the　cost　function.　©　2019　IEEE.