The invention discloses a fluorescent compound using pyrochlore structure metatitanic acid lanthanum as a substrate. The general formula of the fluorescent compound is La2(1-x)M2xTiO5, wherein M is Dy and/or Sm, x is greater than or equal to 0.01, and x is less than or equal to 0.02. The preparation method comprises the following steps: dissolving the soluble salt La and the soluble salt of Sm and/or Dy in the deionized water, and obtaining solution A; mixing tetrabutyl titanate and alcohol to obtain solution B; mixing the solution A and the solution B, dripping acid and stirring to obtain solution C, rising the temperature of the solution to 50-150 DEG C and keeping the temperature, and obtaining precursor gel; roasting the precursor gel, and obtaining a calcined material; and smashing, grinding, washing and drying the calcined material, and obtaining the fluorescent compound, wherein the fluorescent compound can be used for preparing the luminescent material for white light LED. The fluorescent compound has the characters of good luminescent performance, high luminescent intensity, and better color rendering. The preparation method has the characters of low calcinations temperature, simple process and low cost, and is capable of satisfying the requirement of the white light LED illumination field.