Deep-ultraviolet photoluminescence technique is used to investigate the band gaps of AlxGa1-xN epitaxial films. The bowing parameter of AlxGa1-xN is studied by CASTEP module of Material Studio simulation software and the Al molar fractions of AlxGa1-xN epitaxial films are researched. The result shows that the HeAg laser with 224.3 nm emission wavelength can make AlxGa1-xN material produce luminescence. The bowing parameter of AlxGa1-xN epitaxial film is calculated with CASTEP software simulation to be 1.01462±0.06772 eV, from which we can calculate the Al molar fractions of AlxGa1-xN epitaxial films.