Energy absorption by Xe,Ar,He atomic clusters are investigated using laser pulses with 5mJ energy in 150fs duration.Experimental results show that the size of cluster and laser absorption efficiency are strongly dependent on several factors,such as the working pressure of pulse valve,atomic number Z of the gas.Absorption fraction of Xe clusters is as high as 45% at a laser intensity of 1×1015W/cm2 with 20×105Pa gas jet backing pressure.Absorption of the atomic clusters is greatly reduced by introducing pre-pulses.Ion energy measurements confirm that the efficient energy deposition results in a plasma with very high ion temperature.