Abstract: <SPAN lang=EN-US>New technology of preparing sodium dihydrogen phosphate by extraction method with purified wet-process phosphoric acid and sodium chloride as raw materials was studied.An extractant that has low water solubility,high extract- efficiency and good selectivity for hydrochloric acid extraction was found.The influences of extraction temperature,extraction time,amount-of-substance ratio of extractant to sodium chloride,and addition amount of diluting agent etc.on the extraction rate and distribution ratio were also analyzed.Better technological conditions were obtained through single-factor test:extraction temperature was <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="50" UnitName="℃">50 <SPAN lang=EN-US style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman""><SPAN lang=EN-US>℃</SPAN></SPAN></st1:chmetcnv>;extraction time was 20 min;amount-of-substance ratio of phosphoric acid to sodium chloride was 1.0~1.2;amount-of-substance ratio of the extractant to sodium chloride was 1.2~1.3</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman"">；</SPAN><SPAN lang=EN-US>amount of diluting agent was 3%~20% (volume fraction) re-extraction time was 15 min;under these conditions P</SPAN><SPAN lang=EN-US><SUB>2</SUB>O</SPAN><SPAN lang=EN-US><SUB>5</SUB> yield could reach </SPAN><SPAN lang=EN-US>95.64%,</SPAN><SPAN lang=EN-US>purity of sodium dihydrogen phosphate dihydrate was more than 99.5% and mass fraction of chlorine ion was less than </SPAN><SPAN lang=EN-US>0.1%.<BR></SPAN>