The main composition of a butylene oxidative dehydrogenation used for fixed beds is AaBbCcDd.FexOe, wherein a is 2-10, b is 0.01-0.1, c is 0.01-0.5, d is 0.01-0.5, x is 6-20, e is a value meeting valence requirements, A is Cr, Co or Cu, B is W, C is Ca, Mg, Sr or Ba, and D is K, V or Zn. The invention also provides a preparation method of the catalyst. The method comprises the following steps: processing metal precursors, sequentially adding the processed precursors to a certain concentration of an iron nitrate solution, reacting, and adding a certain amount of a binder to obtain a precursor precipitate slurry; gradually adding ammonia water to the slurry to adjust the pH value of the slurry; carrying out thermal modification on the slurry at a certain temperature; filtering and washing the slurry, filtering the slurry, and carrying out strip extrusion molding; and carrying out roasting modification at 100-500DEG C for 12-28h to obtain the finished catalyst.