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">Yttria precursor was prepared with ammonia and yttrium nitrate as raw materials.Effects of surfactants and their dosage on morphology and size of the crystals were researched.Effect of pH,temperature,and time on reforming precipitate was also studied under hydrothermal conditions.Crystal form,size,and morphology of sample were investigated by XRD and SEM.Results showed that the size of the first level crystal grains was relatively obviously affected by concentration of anion surfactant,while the effects of concentration of cation and non-ion surfactants on it was insignificant.Yttrium hydroxide nanorods could be obtained by reforming the precipitate under hydrothermal conditions and the diameter and length of nanorods were dependent on alkalinity and temperature of solution and time of reaction.Cubic crystal phase yttria was obtained by calcination the sample for 2 h at 600 </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"> and the first level crystal grains ranging from 7 to 20 nm.Yttria which came from the calcination of yttrium hydroxide nanorods still had rod-like structure.</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>