The invention discloses a double-beam delayed laser damage testing system. The system is composed of a pulse laser, a laser controller, seven reflecting mirrors, four light splitters, two annular changeable neutral-density filtering sheets, an electrically controlled translation platform, a motor driver, a main control computer, an electronic shutter, two plano-convex lenses, a three-dimensional electrically controlled sample platform, a beam quality analyzer, an energy detector, a high-resolution color CCD imaging device and a white light source. With the utilization of the computer, the double-beam delayed laser damage testing system realizes automatic control by utilizing the computer, and can perform laser damage threshold testing of lasers in different pulse widths on the surface of an optical element.