The improvement of the uniformity of on-target irradiation has long been a critical task for Inertial confinement fusion(ICF) laser driver.A number of smoothing techniques have been developed in the past decades.Spatial techniques can control the target spot envelope and improve the irradiation uniformity of large spatial scale,while temporal techniques can smooth the beam by eliminating intensity modulation of short wavelength inside the spot.A comprehensive review on this field is made,and a brief introduction of the smoothing requirements for the facility “SG Ⅱ” is given,as well as the development of smoothing techniques used in it.