Bisphosphine monoxide ligand 1 with a methylene linker was applied to the nickel catalyzed olefin polymerization. In situ generated phenylnickel chloride complex 2 and NaBAr4F mediated the homopolymerization of ethylene and propylene. In addition, complex 2 and NaBAr4F produced the copolymer of those nonpolar olefins with allyl acetate. Cationic eta(3)-allylnickel complex 3 was successfully isolated and characterized by X-ray crystallographic analysis. Complex 3 exhibited square planar geometry with a bite angle close to 90 deg. Although a strong Lewis acidic cocatalyst such as ZnEt2, B(C6F5)(3), or methylaluminoxane was required for the activation, complex 3 could also copolymerize nonpolar olefins with allyl acetate.