Abstract: W-type barium-ferrite BaCo<SUB>2</SUB>Fe<SUB>16</SUB>O<SUB>27</SUB>andBa<SUB>1-x</SUB>La<SUB>x</SUB>Co<SUB>2</SUB>Fe<SUB>16</SUB>O<SUB>27 </SUB>were synthesized by sol-gel method with barium nitrate [Ba(NO<SUB>3</SUB>)<SUB>2</SUB>],cobalt nitrate [Co(NO<SUB>3</SUB>)<SUB>2</SUB>·6H<SUB>2</SUB>O],ferric nitrate [Fe(NO<SUB>3</SUB>)<SUB>3</SUB>·9H<SUB>2</SUB>O],lanthanum nitrate [La(NO<SUB>3</SUB>)<SUB>3</SUB>·6H<SUB>2</SUB>O] and citric acid [C<SUB>6</SUB>H<SUB>8</SUB>O<SUB>7</SUB>·H<SUB>2</SUB>O] as raw materials.The product was characterized by TG/SDTA,XRD, and IR.Influence of sintering temperature and rare earth element lanthanum (La) doping on crystal structure was also studied.Results showed that the product was single phase hexagonal crystal system BaCo<SUB>2</SUB>Fe<SUB>16</SUB>O<SUB>27</SUB> ferrite and did not contain M-type barium-ferrite BaFe<SUB>12</SUB>O<SUB>19</SUB>and CoFe<SUB>2</SUB>O<SUB>4</SUB> when sintering temperatqiaure reached 1 250 ℃ in preparation process of BaCo<SUB>2</SUB>Fe<SUB>16</SUB>O<SUB>27</SUB>.In rare earth element La doping experiment,because&nbsp;La<SUP>3+</SUP> was mixed,new absorption peaks of Fe<SUP>2+</SUP>—O and La—O emerged in about 500cm<SUP>-1</SUP>and 475cm<SUP>-1</SUP> in IR pattern. In addition,doping of rare earth element La also had some influences on unit cell parameters.