A new lithium salt electride with an excess electron pair is designed, for the first time, by means of doping two sodium atoms into the lithium salt of pyridazine. For this series of electride molecules, the structures with all real frequencies and the static first hyperpolarizability (beta(0)) are obtained at the second-order Moller-Plesset theory (MP2). Pyridazine H4C4N2 becomes the lithium salt of pyridazine Li-H3C4N2 as one H atom is substituted by Li. The lithium salt effect on hyperpolarizability is observed as the beta(0) value is increased by about 170 times from 5 to 859 au. For the electride effect, an electride H4C4N2 center dot center dot center dot Na-2 formed by doping two Na atoms into pyridazine, the beta(0) value is increased by about 3000 times from 5 to 1.5 x 10(4) au. Furthermore, combining these two effects, that is, lithium salt effect and electride effect, more significant increase in beta(0) is expected. A new lithium salt electride Li-H3C4N2... Na-2 is thus designed by doping two Na atoms into Li-H3C4N2- It is found that the new lithium salt electride, Li-H3C4N2 center dot center dot center dot Na-2, has a very large beta(0) value (1.412 x 10(6) au). The beta(0) value is 2.8 x 10(5) times larger than that of H4C4N2, 1644 times larger than that of Li-H3C4N2, and still 93 times larger than that of the electride H4C4N2 center dot center dot center dot Na-2. This extraordinary beta(0) value is a new record and comes from its small transition energy and large difference in the dipole moments between the ground state and the excited state. The frequency-dependent beta is also obtained, and it shows almost the same trends as H4C4N2 << Li-H3C4N2 << H4C4N2 center dot center dot center dot Na-2 << Li-H3C4N2 center dot center dot center dot Na-2. This work proposes a new idea to design potential candidate molecules with high-performance NLO properties.