InSb is an important non-carbon-bearing anode material for lithium (ion) batteri es. An ab initiomethod with first-principles pseudopotentials based on the density functional theory has been used to calculate the total energies, formation energies and equi librium volumes of Li intercalations in InSb in 125 possible cases. Comp aring with the experimental voltage profile curve, we have picked out the possib le reaction routes of Li insertions in InSb and a theoretical voltage pr ofile curve is reached. Our results show that, from bulk InSb to bulk Li＿3Sb, the re are no possible reaction routes undergoing five or more intermediate ph ases. The most favored route for undergoing only one intermediate phase is Li+In＿4Sb＿4→Li＿1In＿4Sb＿4,11Li+Li＿1In＿4Sb＿4→Li＿12Sb＿4+4In；whereas there exists only one reaction route for undergoing four intermediate phases, that is, Li+In＿4Sb＿4→Li＿1In＿4Sb＿4,2Li+Li＿1In＿4Sb＿4→ Li＿3In＿4Sb＿4,4Li+Li＿3In＿4Sb＿4→Li＿7In＿3Sb＿4+In,3Li+Li＿7In＿3Sb＿4→Li＿10In＿2Sb＿4+In,2Li+Li＿10In＿2Sb＿4→Li＿12Sb＿4+2In..