Abstract: Tri-compound AlxGa1-xAs films was prepared by using electrodeposition technology in simple salt solution with additives citric acid. The composition of the deposited films was measured by SEM-EDS. The result shows that approximately stoichiometric Al_0.3Ga_0.7As tri-compound semicon- ductor materials is obtained. As the films are measured by spectrophotometer, certain transmissivity is obtained in a wide range of light wave band.