C70 is the second most abundant fullerene next to C60. In this work, the exploration of C70 based electrides is proposed by theoretical encapsulation of group I/II trimetallic clusters into the C70 cage. Herein, we provide computational evidence that endohedral metallofullerenes M3@C70 (M = Li, Na, K, Be, Mg, Ca, Sr, Ba) can exist stably by calculating encapsulation energies and analyzing atom centered density matrix propagation molecular dynamics simulations. According to the results of the atoms in molecules analysis, electron localization functions and nonlinear optical properties, M3@C70 (M = Li, Be, Mg, Ca) fullerenes are identified as electrides. Interestingly, Li3@C70 and Be3@C70 are the systems with better electride performances among alkali metal and alkaline earth metal systems, respectively. It is worth noting that C70 can improve the polarizability and first hyperpolarizability of electrides compared with C60. Our work unearths the potential of M3@C70 electride systems and paves the way for the research of C70-based electrides.