The functionalized covalent organic framework materials play an important role in catalytic application. A convenient tactic is developed to design and synthesize an imine‐linked covalent organic frameworks (COFs) material (COF‐PD) with abundant nitrogen atoms, which can provide coordination active site and facilitate the incorporation of COFs with nickel ions. Nickel‐coordinated COF‐PD complex (COF‐PD‐Ni) is prepared and used in ethylene oligomerization. COF‐PD‐Ni displays the highest catalytic activity of 1.98 × 105 g/(mol·Ni·h) in ethylene oligomerization with MAO as co‐catalyst and cyclohexane as solvent. Various reaction parameters including reaction temperature, time, solvent, and the amount of cocatalyst are evaluated in detail, dramatically impacting the catalytic activities as well as the distribution of the products. What is more, the effect of COFs structure on the catalytic performance is also studied, suggesting more coordination sites were more important for high activity. An imine‐linked covalent organic frameworks (COFs) material (COF‐PD) with abundant nitrogen atoms and large surface area was synthesized to provide coordination active site and facilitate the incorporation of COFs with nickel ions to form nickel‐coordinated COF‐PD complex (COF‐PD‐Ni). The large surface area of COF‐PD‐Ni was far lower than that of COF‐PD before loading nickel because of pore blockage caused by the coordination of Ni2+. COF‐PD‐Ni displayed excellent catalytic activity with a strong preference for the 1‐butene in ethylene oligomerization, which attributed to the faster rate of chain transferring process than the chain propagation because of the confinement effect aroused by pore features of covalent organic frameworks.