The present invention provides a ray beam guiding device for guiding a ray beam in a ray inspection apparatus. The ray beam guiding device is provided in a housing of the ray inspection apparatus, and two ends of the ray beam guiding device are connected to a front collimator and a rear collimator, respectively. The ray beam guiding device comprises a plurality of guiding walls and a guiding cavity surrounded by the guiding walls. The guiding wall is formed of a first material which is capable of absorbing rays or the first material is coated on an inside of the guiding wall, and the guiding cavity has a central axis extending in a direction from the rear collimator to the front collimator, and the ray beam guiding device further comprises at least one fin plate provided in the guiding cavity of the ray beam guiding device. The at least one fin plate is configured for blocking and/or absorbing scattered rays.