The velocity of lithium iron across the entrance of carbon nanotube VLi is an important factor for the charge performance of lithium iron battery. The molecular dynamics simulation is adopted to evaluate the effects of control factors which include electric strength, functional group type, the diameter of carbon nanotube and temperature. By the L16(45) orthogonal array method, the simulations are carried out. The order of influences of control factors is electric filed intensity > functional group > diameter > temperature. Within the ranges of the control factors studied in this work, VLi increases with increasing the diameter of carbon nanotube and electric field strength. VLi decreases with successively modifying the functional groups at the end of carbon nanotube into -H, -OH, -NH2 and -COOH. With the increasing of temperature, VLi first increases then decreases, but on the whole its change is not big.