The present invention discloses a ray beam guiding apparatus, comprising a ray beam guiding box having substantially fan-shaped top and bottom surfaces, defining an inner space, and having open wide and narrow ends; an engaging member joined to the narrow end of the box; a first collimator mounted to the box adjacent to the narrow end for adjusting size/shape of the ray beam in horizontal vertical direction; a second collimator having a calibration slit or grill and mounted to the box adjacent to the wide end; and an adjusting member connecting the engaging member and a ray generator to adjust a distance therebetween. The box can adjust size/shape and centering of the ray beam, so that inspection quality can be improved and thickness of the ray shielding layer can be reduced, the box is applicable to a ray inspection system which performs security inspection of liquid articles.