  The effect of electric and color neutrality on 2-flavor color
superconductivity has been investigated. It has been found that the effect of
the charge neutrality on a 2-flavor quark system is very different from that on
a 3-flavor system. The BCS diquark pair in 2-flavor color superconducting phase
has been largely reduced by the large Fermi momentum of electron, the diquark
condensate first increases with the increasing of quark's chemical potential
$\mu$,then decreases rapidly and finally disappears at about $\mu=535MeV$, at
which the thermodynamic potential equals to that in the neutral normal 2-flavor
quark matter.
