A detection apparatus and method for testing optical performance of beam shaping element used in ultraviolet lithography machine; The apparatus comprises visible wavelength laser and other optical units placed along the optical axis including, in order from laser side, (a) beam expander lens group, (b) beam splitter, (c) first far field imaging lens, (d) adjustable aperture or (e) CCD image sensor, (f) second far field imaging lens and (g) energy sensor. The detection apparatus is suitable be employed to detect the optical performance of beam shaping element working at any ultraviolet band, and provides the features of low cost, easy operation and quick measurement.