Electrodeposition of Cu–Li alloy from 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) ionic liquid was investigated. The cyclic voltammetry behaviors of [BMIm][BF4] containing Cu(II), Li(I), and mixtures of Cu(II) and Li(I) were studied at a copper working electrode, separately. The Cu–Li alloy produced by direct current electrodeposition was characterized by inductively coupled plasma atomic emission spectrometry (ICP), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The function of 2-butyne-1,4-diol was studied by linear sweep voltammetry. The result shows that the 2-butyne-1,4-diol could improve Li content in deposit, and make the Cu–Li alloy deposits denser and finer.