The electron energies were measured to investigate the influences of laser intensity and wavelength on the ion charge state distribution of Cq+ (q = 2-4) when benzene clusters were irradiated by 10(9)-10(11) W/cm(2) nanosecond laser pulses. The results show that the ratios of Cq+/C-(q (1)+) strongly depend on laser wavelength but slightly on laser intensity. The mean electron energy up to 100 eV was measured, which was qualitatively consisted with the 'multiphoton ionization ignition-inverse bremsstrahlung heating-electron impact ionization' three-stage model. The screening effects inside clusters can significantly decrease the ionization potentials of Cq+ and facilitate the formation of multiply charged ions especially at low laser intensity. (C) 2008 Elsevier B. V. All rights reserved.