Research　of　seawater　and　sea　sand　concrete　(SWSSC)　is　the　current　hot　topic,　but　effects　of　water-cement　ratios　(W/C)　on　alkali-silica　reaction　(ASR)　of　SWSSC　haven＇t　been　investigated.　To　solve　this　issue,　the　ASR　products,　pore　structure　and　expansion　rate　of　specimens　with　different　W/C　(0.35　similar　to　0.55)　were　measured.　The　study　shows　that　pore　structure　and　Na+　consumption　are　two　key　factors　influencing　ASR　of　SWSSC.　When　the　W/C　increases　from　0.45　to　0.55,　Na+　in　specimen　replaces　K+　in　ASR-P1(K0.52Ca1.16Si4O8(OH)(2.84)center　dot　1.5H(2)O),　and　ASR-P1　is　converted　into　Na-shlykovite(NaCaSi4O8(OH)(3)center　dot　2.3H(2)O);　the　porosity　is　the　dominant　factor　for　the　expansion　rate　of　SWSSC.　When　the　W/C　increases　from　0.35　to　0.45,　the　Na+　consumption　is　the　dominant　factor　for　the　expansion　rate　of　SWSSC.　Magnesium　element　mainly　coexists　in　Na-shlykovite　and　transition　zone　in　SWSSC　with　W/C　=　0.55.　The　research　results　are　beneficial　to　inhibit　ASR　of　SWSSC　with　different　W/C　and　improve　their　durability.