Phthalic　acid　esters　(PAEs)　are　commonly　used　as　plasticizer　and　are　emerging　concern　worldwide　for　potent　adverse　effects　of　aquatic　organisms.　Certain　PAEs　were　often　detected　in　different　environmental　matrices　but　related　toxicity　data　were　still　lacking　to　support　their　risk　assessment.　The　study　investigated　the　acute　toxicity　of　Diisobutyl　phthalate　(DiBP)　and　Di-n-octyl　phthalate　(DnOP)　using　6　Chinese　resident　aquatic　organisms　from　3　phyla　and　6　species　and　constructed　the　species　sensitivity　distribution　(SSD)　models　for　ecological　risk　assessment.　Lethal　concentration　50%　(LC50)　ranges　of　DiBP　and　DnOP　were　4.89-21.45　mg/L　and　1.45-1200　mg/L,　respectively.　The　derived　acute　and　chronic　predicted　no-effect　concentrations　(PNECs)　based　on　log-normal　model　of　water　were　0.54　and　0.04　mg/L　for　DiBP　and　0.23　and　0.05　mg/L　for　DnOP,　respectively.　The　ERA　for　DiBP　and　DnOP　in　the　surface　water　and　sediment　of　China　was　conducted.　Water　samples　of　Haihe　Rive　(RQ　=　0.41)　and　Hun　River　(RQ　=　0.16)　of　DiBP　showed　medium　risk.　And　sediment　samples　of　Yellow　River　(RQ　=　0.71)　and　Chao　Hu　Lake　(RQ　=　0.42)　of　DiBP　showed　medium　risk.　Meanwhile,　the　above　water　and　sediment　samples　(RQ　＜　0.1)　of　DnOP　showed　low　risk.