A series of higher 2-alkenes, i.e., 2-pentene, 2-hexene and 2-octene were polymerized with phenyl substituted α-diimine nickel complexes in combination with modified methylaluminoxane (MMAO) to produce branched poly(2-alkene)s with high molecular weight and narrow molecular weight distribution (M_w/M_n < 1.8). At 0 °C, these 2-alkenes polymerized in a living manner to produce amorphous polymers with glass transition temperature of –70 ∼ –65 °C. The microstructures of the produced polymers indicated the 2,3- and 3,2-insertion followed by chain-walking and the incorporation of a small amount of 1-alkene formed by isomerization. The branch structures were significantly depended on the polymerization temperature, and the ratio of methyl branch predominantly derived from 3,2-insertion was increased with increasing the polymerization temperature.