Through the examination of L12 type superconductors, we obtained the expression for the superconducting critical temperature Tc of L12 type superconductors: Tc=(15.9TBV(B)GA)/(M1/2 V(L12)GB) where TB is the superconducting critical temperature of pure B, V(B) is the atomie volume of pure B, V (L12) is the average atomic volume of the L12 type compound, M is the average atomic wight of the compound, and GA ,GB are Gordy electronegative values.