A new type of neodymium-doped lanthanum fluoride (LaF3Nd) nanoparticles are synthesized by hydrothermal method. It exhibits hexagonal structure and a size of about 25 nm. A series of different concentrations of LaF3Nd nanoparticles dispersion are prepared by ultrasonic technology. The visible-near-infrared spectra show that the dispersion with the optical path of 5 mm and neodymium ion concentration of 1×1020 cm-3 shows high transmittance of 85% at 1053 nm. The lifetime of the La0.95Nd0.05F3 nanoparticles dispersion is 200 μs, compared with that of the powder, it is reduced by 3.8%. These results indicate that the LaF3Nd nanoparticles dispersion with low fluorescence quenching rate, high ion concentration and high transmittance is a kind of promising material used for high repetition rate, high-power and ultra short pulse liquid laser.