Abstract: In order to understand the impact of sunlight exposure on adhesion between coats and glass fiber reinforced composite wind turbine blade,the glass fiber reinforced epoxy resin composites samples are exposed in sunlight for different time,then PU gel-coating are coated on them and the effect of sunlight aging on the adhesion strength between GFRP composites and gel-coatings is investigated in pull-off method.The results show that the adhesion strength of gel-coating decreases from about 9 MPa to about 7 MPa,corresponded to light-aging time from 0 day to 5 days,and then decreases sharply after 6 days light-aging.