The invention provides a quinoline-benzimidazole IVB group mono-Cp complex, a preparation method and application thereof and a method for polymerization reaction of olefin. The quinoline-benzimidazole IVB group mono-Cp complex adopts the structure shown in a formula (I), wherein R<1> refers to C1-C3 alkyl; R<2>-R<5> respectively and independently refer to H, C1-C3 alkyl or halogen, R<6> refers to H or C1-C3 alkyl; Cp' refers to substituted or non-substituted cyclopentadienyl. A 2-benzimidazole-8-hydroxyquinoline mono-Cp titanocene complex provided by the invention has higher catalysis reactivity, so ethylene homopolymerisation, and ethylene and alpha-olefin copolymerization are catalyzed better. In addition, under the condition of 150 DEG C, 0.04 g of a polymer obtained through catalysis of the complex is placed in 50 mL of 1,3,5-trichlorobenzene, and the solubility of the polymer is less than 0.05wt%, so the result shows that the obtained polymer is a super-high molecular weight polymer. (The formula (1) is shown in the Specification).