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As alternatives to Yb 3+ -sensitized up-conversion (UC) materials excited at 980 nm, Nd 3+ -sensitized UC phosphors irradiated by 808 nm have been used to decrease the absorption of water and alleviate the overheating effect in vivo biological application. Intense red and green UC emissions from 5 F 5 → 5 I 8 and 5 F 4 / 5 S 2 → 5 I 8 transitions of Ho 3+ appeared in Nd 3+ /Yb 3+ /Ho 3+ tri-doped NaLa(MoO 4 ) 2 through successive energy transfer Nd 3+ →Yb 3+ →Ho 3+ under 808 nm excitation, in which Yb 3+ ions were proven to be the energy transfer bridge between Nd 3+ and Ho 3+ by lifetime measurement. The variable emission color and intensity ratios of red to green emissions were realized by adjusting the doping concentration of Yb 3+ , pulse width of the excitation laser and the addition of Ce 3+ ion, which depends on the different population pathways to the green and red emitting states of Ho 3+ . The chromaticity modulation mechanisms of these approaches were proposed, which provides a feasible strategy to tune the UC emission color. [ABSTRACT FROM AUTHOR]