The pseudopotential investigation of the electronic structure of liquid alkali metals has been described. A new six-parameter model for electron-ion interaction potential has been developed on the basis of well known pseudo-spherical mathematical function S(l)(x). The deviations of Fermi energy and electronic mass from free electron value have been described for alkali metals. It has been observed that there is deviation in the liquid phase values from the corresponding solid phase values, which shows that the departure is due to the insignificant change in the density of state. The Fermi energy behaviour of Li is quite different than one class of alkali metals Rb and Cs and another class of metals Na and K. There is significant deviation of electronic mass in case of Li, K, Rb and Cs metals at the melting point. A large deviation exists in case of Li and Cs which appears due to abnormal change in the atomic volume of these metals at the melting point. No change occurs in case of Na, which shows that the spherical Fermi surface does not change during melting, which is quite a different observation from other members of the group.