Gold nanoparticles dispersion is prepared by dispersing 20nm or even smaller gold nanoparticles into water solution. The preparation will end up with uniform neutral solution with stable color. The gold nanoparticles solution appears to be faint red not golden brown. The gold nanoparticles solution appears to be azury when in condensed state by adding other substance. The solution is edible for human beings and totally safe for skin contact. Like silver nanoparticles, Au nanoparticles are resistant to antibiotics.