In　this　work,　different　types　of　sea　sand　were　used　to　study　the　effect　of　multi-substance　film　of　sea　sand　on　mechanical　properties　and　durability　of　mortar.　First　the　flexural　strength　and　compressive　strength　of　mortars　made　with　unwashed　sea　sand,　washed　sea　sand　and　river　sand　were　evaluated　from　1　day　to　180　days　of　standard　curing.　The　results　indicated　that　both　strengths　of　mortars　made　with　washed　sea　sand　were　the　highest,　followed　by　river　sand　mortars,　mortars　made　with　unwashed　sea　sand　were　the　lowest,　after　180　days　of　curing.　Then　the　effect　of　thermal　curing　on　strength　of　mortars　made　with　different　sand　was　studied　and　the　strength　ratio　of　mortars　after　50　​°C　curing　with　respect　to　that　after　standard　curing　was　evaluated.　The　results　indicated　that　thermal　curing　promoted　the　early　strength　of　mortars,　while　decreased　the　late　strength　of　mortars.　The　strength　ratio　of　mortars　made　with　fully　washed　sea　sand　was　the　highest.　Finally　the　freeze–thaw　resistance　of　mortars　was　assessed.　The　results　demonstrated　that　the　mass　loss　and　strength　loss　of　mortars　made　with　fully　washed　sea　sand　were　small.　Whereas　the　mass　loss　of　mortars　made　with　not　fully　washed　sea　sand　increased　linearly　as　freeze-thaw　cycle　increased.　And　their　losses　of　flexural　strength　and　compressive　strength　were　both　considerable,　reaching　24.3%　and　31.4%,　after　450　freeze-thaw　cycles.　Overall　the　multi-substance　film　of　sea　sand　was　harmful　to　thermal　curing　resistance　and　freeze–thaw　resistance　of　mortar.　©　2020