The invention belongs to the technical field of catalyst for use in synthesis of pentenenitrle by using butadiene and particularly relates to a complex catalyst for use in the synthesis of pentenenitrle by the hydrocyanation of butadiene and a preparation method thereof. The chemical formula of the complex catalyst is MXnLm, wherein the M may be Cu, Ag, Zn, Cd, Fe, Co or Ni; the x may be one or combination of more of Cl<->, Br<-> and I<->; the L may be one or combination of several of pyrrole, iminazole, aminopyridine, 4-phenylpyridine, triphenylphosphine, n-methyl pyrrolidone, polyvinyl pyridine, polyvinylpyrrolidone, polyethylene glycol, polyacrylamide, polymethylamine and polythiophene; and the m, which is a coordinate number, is 1 to 12; and the n is a chemical valence balance number.The complex catalyst causes low corrosion to a reactor, so the reaction kettle has no anticorrosion liner; and the complex catalyst has long service life and high activity and selectivity.