Physicochemical property data, such as density, electrical conductivity, and pH of aqueous solutions of LiB(OH)(4), Li2B4O5(OH)(4), and LiB5O6(OH)(4) have been accurately determined at different temperatures. Density values were given from 288.15 K to 323.15 K, and pH and electrical conductivity from 293.15 K to 323.15 K. The properties were represented by semiempirical equations as functions of concentration. The mole fractions of polyborates were obtained in aqueous lithium borate solutions, and their distribution and relevant mechanism were also suggested.