With　the　development　of　modem　monitoring　technologies,　much　physical　and　mechanical　information　of　bridge　state　is　available.　To　use　the　information　to　a　great　extent,　the　study　on　damage　assessment　of　deck　is　much　more　important.　Based　on　the　field　monitoring　data,　this　study　conducts　the　research　on　the　damage　assessment　and　safety　influential　factors　of　concrete　bridge　deck　slab　by　use　of　fuzzy　theory.　First　the　fuzzy　classified　membership　function　is　determined.　Then　the　weight　of　each　index　is　determined　in　the　paper,　e.　g.　the　traffic　volume,　service　year,　time　interval　and　temperature.　Finally,　the　damage　assessment　system　of　concrete　bridge　deck　slab　is　established.　The　damage　assessment　system　can　provide　reference　to　the　bridge　repaired　or　rebuilt.