Abstract: HfN_xO_y films were deposited on three different substrates（Si,Zn,Ni） using DC sputtering method and their field emission characteristics were investigated.SEM shows that the surface of the films is formed by nanoparticles.XRD spectra indicate that there are both HfN phase and HfN_xO_y phase existing in the films.The field emission results show that compared with the flims grown on the metal substrates,the threshold field of the film grown on Si substrate is smaller and the emission current density is bigger.The differences of emission current densities of the three substrates are detailedly discussed.The relation of current versus time shows that the HfN_xO_y film has good current stability.