Abstract: <SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: "Times New Roman"; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">Method of oxidizing phosphorous acid in waste liquid of refining yellow phosphorus on the basis of arsenic removing was studied with H<SUB>2</SUB>O<SUB>2</SUB> as oxidant.Influences of the factors,such as amount of oxidant,pH,reaction temperature,reaction time,and stirring speed,on oxidation rate to phosphorous acid were investigated.Results showed that phosphorous acid in waste liquid of yellow phosphorus refining could be oxidized by H<SUB>2</SUB>O<SUB>2</SUB> into phosphoric acid and oxidation rate reached 85.44%.Optimum process conditions for oxidation were as follows:amount of dearsenification agent H<SUB>2</SUB>O<SUB>2</SUB> was 30 mL, reaction pH was 9,reaction temperature was 80 </SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman"; mso-bidi-font-family: "Times New Roman"; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">℃</SPAN><SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: "Times New Roman"; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">,reaction time was 90 min,and stirring speed was 400 r/min when the amount of waste liquid to be treated was 100 mL.</SPAN>