The multiple linear regression analysis is performed to investigate both electronic and steric effects of ligands on the catalytic activities of the transition metal complexes in ethylene oligo/polymerization. The Hammett constants (F) and effective net charge (Q) are used to describe the electronic effect, meanwhile the steric effect is illustrated by open cone angle (theta) and bite angle (beta). Four series of 2-azacyclyl-6-aryliminopyridylmetal (Fe, Co, and Cr) analog complexes are calculated and the catalytic activity can be efficiently analyzed through taking both the electronic and steric effects into account. All of the obtained correlation coefficient R-2 values are over 0.93. The electronic effect is dominant in determining the catalytic activities for Fe and Co complexes; however, the steric effect plays a major role in controlling activities of Cr complexes.