Hexagonal shaped LaF3 nanocrystals (NC) doped by Nd3+ and Sm3+ ions were synthesized using a domestic microwave oven. The powder XRD study confirmed that the crystalline size of the particle was approximately 20 nm (JCPDS standard card (32-0483) of pure hexagonal LaF3 crystals). The Transmission Electron Microscope (TEM) analysis indicated the size of the primary and secondary particles were between 15-20 nm. The presence of fundamental groups was verified by FTIR spectra. The synthesized nanocrystals were also studied for Non-Linear Optical (NLO) properties. The Second Harmonic Generation (SHG) efficiencies of LaF3 : Nd3+, Sm3+ containing rare earth elements were found to be less than that of pure Potassium Dihydroxyl Phosphate (KDP) crystals.