In this paper, the electron emission from a cathode with a large number of emission sites is discussed by introducing a distribution function of the field enhancement factor beta. After accounting for the distribution of the field enhancement factor, the field electron emission from the cathode deviates from the classical Fowler-Nordheim (F-N) theory, the F-N plot is not a straight line and bends up in region of low electric field. A good agreement of the calculated results with experimental results was achieved by employing a reasonable distribution function of beta. (c) 2005 Elsevier B.V. All rights reserved.