A low-dimensional metal frequently exhibits a metal-insulator transition through a charge-density-wave (CDW) or a spin-density-wave (SDW) which accompany it's structural changes. The transition temperature is thought to be determined by the amount of energy produced during the transition process and the softness of the original structure. AMo4O6 (A=K, Sn) are known to be quasi-one dimensional metals which exhibit metal-insulator transitions. The difference of the transition temperatures between KMo4O6 and SnMo4O6 (A=K, Sn) is examined by investigating their electronic and structural properties. Fermi surface nesting area and the lattice softness are the governing factors to determine the metal-insulator transition temperature in AMo4O6 compounds.