We grew LiNbO3:Fe fibers along the c-axis [0 0 .1] with an iron-doping concentration ranging from 0.18 to 1.08 mol% using the LHPG method. The influence of heavy Fe-doping on LiNbO3 fibers was investigated by means of the infrared technique and polishing. We found that LiNbO3 fibers doped with larger amounts of iron would exhibit larger residual stress. Also, during growth, heavy Fe-doping would flatten the curvature of the growth interface and increase the chance of bubble-entrapment. Nevertheless, heavier Fe-doping was favorable for downward growth because the crystals would have a larger meniscus angle.