A method for estimating weight of an object to be inspected in an inspection system, the method comprising the steps of: obtaining an effective atomic number and a dual-energy high-energy grayscale feature value corresponding to each pixel on an image of the object to be inspected by a dual-energy radiation scanning; and obtaining a mass-thickness value for a corresponding pixel from a pre-created mass-thickness attenuation curve by utilizing the effective atomic numbers and the dual-energy high-energy grayscale feature value for respective pixels; characterized in that the method further comprises the steps of: calculating weight information for at least a part of the object to be inspected by multiplying the mass-thickness value by the area of the pixel; estimating a physical dimension corresponding to each pixel on an image of the object to be inspected in a direction in which detectors are arranged, based on a pitch between detector pixels, a distance between an X-ray source and the detectors, and a distance between the X-ray source and the object to be inspected; obtaining a pixel physical dimension in a scanning direction based on a scanning speed and an acquiring frequency of the detectors; and obtaining the area of each pixel by multiplying the physical dimension corresponding to each pixel on the image of the object to be inspected in a direction in which the detectors are arranged by the pixel physical dimension in the scanning direction. obtaining an effective atomic number and a dual-energy high-energy grayscale feature value corresponding to each pixel on an image of the object to be inspected by a dual-energy radiation scanning; and obtaining a mass-thickness value for a corresponding pixel from a pre-created mass-thickness attenuation curve by utilizing the effective atomic numbers and the dual-energy high-energy grayscale feature value for respective pixels; characterized in that the method further comprises the steps of: calculating weight information for at least a part of the object to be inspected by multiplying the mass-thickness value by the area of the pixel; estimating a physical dimension corresponding to each pixel on an image of the object to be inspected in a direction in which detectors are arranged, based on a pitch between detector pixels, a distance between an X-ray source and the detectors, and a distance between the X-ray source and the object to be inspected; obtaining a pixel physical dimension in a scanning direction based on a scanning speed and an acquiring frequency of the detectors; and obtaining the area of each pixel by multiplying the physical dimension corresponding to each pixel on the image of the object to be inspected in a direction in which the detectors are arranged by the pixel physical dimension in the scanning direction. calculating weight information for at least a part of the object to be inspected by multiplying the mass-thickness value by the area of the pixel; estimating a physical dimension corresponding to each pixel on an image of the object to be inspected in a direction in which detectors are arranged, based on a pitch between detector pixels, a distance between an X-ray source and the detectors, and a distance between the X-ray source and the object to be inspected; obtaining a pixel physical dimension in a scanning direction based on a scanning speed and an acquiring frequency of the detectors; and obtaining the area of each pixel by multiplying the physical dimension corresponding to each pixel on the image of the object to be inspected in a direction in which the detectors are arranged by the pixel physical dimension in the scanning direction.