The invention discloses a ray energy fluctuation correcting method suitable for a high-energy X-ray DR scanning system. The correcting method comprises the following steps of: acquiring reference ray intensity I0(z) of each row of a primary DR image, and performing logarithmic transformation on each row of data in the primary DR image by using the I0(z) to obtain a first transformation DR image I1(y, z); performing column average on the I1(y, z) to obtain a one-dimensional image series p(z), and filtering the p(z) by using a high-pass filter to obtain a high-frequency component pH(z); and finally, subtracting the pH(z) from each column of data in the I1(y, z) to obtain a second transformation DR image I2(y, z), and performing inverse color transformation on the I2(y, z) to obtain a corrected final DR image Icorr(y, z). The correcting method can effectively correct an artifact caused by energy fluctuation of an accelerator so as to improve the quality of images and facilitate interpretation of the images and identification of defects.