Abstract: The present invention relates to a novel linear ?-olefin catalyst composition, and preparation and use thereof. The catalyst composition includes a main catalyst and a co-catalyst, wherein the main catalyst is an imino-based iron coordination compound, and the co-catalyst is a mixture of methylaluminoxane, triisobutylaluminum, and borane or GaCl3. The catalyst composition can be used to catalyze ethylene oligomerization to produce linear ?-olefins having a selectivity of greater than 96%, carbon distribution between C4-C28 with the component of C6-C20 being greater than 75%. The catalyst of the invention is stable in structure and can be used for ethylene oligomerization with high catalytic efficiency. The method of the invention has the advantages of relatively convenient in operation, readily available of raw materials, high yield, low costs, less pollution and easy for industrial production.