A series of novel red emitting phosphors Li 6 M(La 1−x Eu x ) 2 Nb 2 O 12 (M=Ca, Sr, Ba; 0≤x≤0.3) were synthesized by solid state reaction, and their structures and photoluminescence properties were investigated in detail. The excitation spectrum of Li 6 M(La 1−x Eu x ) 2 Nb 2 O 12 revealed two mainly excitation bands at 393nm and 464nm, which match well with the two popular emissions from near-UV and blue LED chips. Upon the 464nm light excitation, Li 6 MLa 2 Nb 2 O 12 :Eu 3+ phosphors exhibit a red emission centered at 608nm, originated from the 5 D 0 – 7 F 2 transition of Eu 3+ ions. The Eu 3+ surrounding crystal lattice environment in the garnet-based host was changed by altering the c sites element with different radii alkaline earth Ba, Sr, and Ca. The evident photoluminescence enhancement was observed in Li 6 M(La 1−x Eu x ) 2 Nb 2 O 12 phosphors with the decreasing of the c sites ionic radius. The emission intensity of the optimized Li 6 Ca(La 0.8 Eu 0.2 ) 2 Nb 2 O 12 (λ exc =464nm) phosphor is about two times higher than that of Y 2 O 3 :Eu 3+ (λ exc =467nm) under blue light excitation. In addition, the quenching mechanism and the relationship between the structure and photoluminescence property were also discussed.