The invention belongs to the field of scintillation crystal materials, especially relating to a codoping modified lithium gadolinium borate scintillation crystal and a preparation method thereof. The codoping modified lithium gadolinium borate scintillation crystal has the following chemical formula: Li6CexNyGd1-x-yB3O9-delta/2Mdelta, wherein, M is selected from one or two elements of F, Cl, Br and I, N is selected from one or two elements of Sc, Y, La and Lu, and at least one of Li element, Gd element and B element exists in the form of special isotope; x is more than 0 and is 0.2 at most, y is 0 at least and is smaller than 1, delta is 0 at least and 0.1 at most, and y and delta can not be 0 at the same time. The preparation method comprises the following steps: raw materials are mixed, synthesized in solid phase and transformed to grow and prepare single crystal form with a pulling method in a single crystal growing furnace. The codoping modified lithium gadolinium borate scintillation crystal of the invention takes Ce ion as an luminous center, and lithium, gadolinium and borate elements exist in one or the combination of Li-6, gadolinium-155, gadolinium-157 or borate-10 isotope so as to perform the function of generating nuclear reaction with the detected neutrons.