Abstract: In order to modify the deviation angle of ultraviolet polarizing prism of iceland crystal and barium fluoride,a new design was given by changing the structure angle of the iceland crystal.The relation between modified angle and structure angle was given at 303nm,and the relation of the deviation angle with wavelength was also investigated.The results obtained by the mathematical software ORIGIN 7.0 indicated that the deviation angle was less than 0.04° in the range of 240nm~410nm.