Abstract: A quantitative method for determination of U and Ce in simulative MOX fuel samples by binary intensity ratio and X-ray fluorescence spectrometry is studied. Pressed powder pellet sample preparation is adopted. The pretreatment of the sample is fast and simple. The mutual interference of the two elements is eliminated efficiently by intensity ratio technique. The relative standard deviation(s_r) of U and Ce is 0.2% and 1.8%, respectively.