To exactly characterize X-ray light resource parameters， a measuring method for the focal spot size and focal depth of an X-ray source was proposed by using a single-bounce ellipsoidal monocapillary X-ray condenser (SBEMXRC). The SBEMXRC was a kind of X-ray reflective imaging optics and characterized by its single total reflection imaging capability. The universal relationship among the focal spot size of the X-ray source， image size of focal spot of the X-ray source and the slope errors of the SBEMXRC was determined by the X-ray sources with known spot sizes simulated by a polycapillary X-ray lens. The focal spot size of the X-ray source with a unknown spot size was accordingly obtained by analyzing image size of the focal spot. The focal depth of the X-ray source could also be measured by the designed method. To verify the feasibility of the designed method， the spot size and the focal depth of a microfocus X-ray source in our lab were measured. The experimental results show that the arithmetic mean standard deviations of the measurement are 1.5 μm and 0.7 mm for the X-ray source with a spot size about 50 μm and a focal depth about 20 mm， respectively. The results demonstrate that the focal spot size and focal depth of the X-ray source could be simultaneously measured with the designed method. This method has potential applications in the field of X-ray sources.