The invention relates to the field of olefin
coordination polymerization, and discloses a method for preparing an
ethylene copolymer. The method is characterized in that
ethylene, a
comonomer and a catalyst are contacted under an
olefin polymerization condition in the presence of an
inert solvent; the catalyst contains a dialkynylphenol-based post-
metallocene catalyst precursor represented by formula (I), a
boride, and an alkylaluminum compound; and in the formula (I), R1 is
hydrogen, a C1-C20 linear or branched
alkyl group or a
trimethylsilyl group, R2 is
hydrogen, a C1-C20 linear or branched
alkyl group or a
phenyl group, R3, R4, R5, R6 and R7 are
hydrogen or a C1-C20 linear or branched
alkyl group, M is one of
titanium,
zirconium and
hafnium, and X1 and X2 can be same to or different from each other, and respectively independently are halogens. The
ethylene copolymer prepared by the method has a high
catalytic efficiency, the introduction proportion of the
comonomer is high, and the preparation process of the post-
metallocene catalyst precursor is simple.