Refined coal pitch is a recognized precursor to produce high-quality needle coke with its higher aromaticity, lower ash content, and a relatively narrow distribution of molecular weight. The aromatic index (f(a)) of refined coal pitch is one of the key roles in the production of high-quality needle coke. In order to a detailed study on the effects of f(a) on the microstructure and properties of needle coke, 9 kinds of refined coal pitches with varied f(a) were used as the raw materials to produce needle coke in this study. Briefly, H-1 NMR was used to calculate the f(a) of each refined coal pitch. Polarizing microscope, scanning electron microscopy, microstrength tester, X-ray diffraction, Raman spectrum, and curve-fitted methods have been used to quantitatively examine the microstructure and microstrength of each needle coke. The results have shown that the refined coal pitch with the f(a) of 0.95 0.98 was the best precursor to produce high-quality needle coke.