Coherence, as a core element of cutting-edge X-ray research technology, has driven the vigorous development of many experiments such as coherent X-ray diffraction imaging and X-ray holography in the past two decades, as well as the construction of fourth-generation synchrotron radiation sources and hard X-ray free electron lasers. To measure the size of synchrotron radiation light source and coherence of beamline, an X-ray measurement system based on two-dimensional (2D) single grating interferometry is established in this work, and the measurement principles and propagation models used in the system are also investigated. Firstly, based on the VanCittert-Zernike theorem, the relationship between the visibility of the interference lattice and the spatial coherence of X-rays is established. Secondly, by combining the Talbot self imaging effect of a single grating, the X-ray spatial coherence length of the grating plane is measured, and the spatial distribution of the corresponding light source is obtained through further calculation. The relevant measurement experiments of this study are conducted at the BL09B bending magnet beamline of the Shanghai Synchrotron Radiation Facility (SSRF). A 2D checkerboard π phase-shift grating is used as the core device in the experiment. This setup can not only enable the acquisition of transverse coherence lengths in the vertical and horizontal directions but also further measure the transverse coherence lengths in the directions forming 45° and 135° angles with respect to the horizontal direction. The experimental process strictly follows the technical specifications outlined in this paper: measuring interferograms at different positions downstream of the phase grating along the beam propagation direction. For each interferogram, the corresponding visibility values are extracted by analyzing the harmonic peaks in its Fourier-transformed image. Ultimately, the transverse coherence length in each direction is derived based on the evolution law of visibility as a function of the grating-to-detector distance. The experimental results show that the coherence length of the emitted X-rays on SSRF testline is 4.2 μm(H)×13.8 μm(V) at 15 keV, and the size of the bending magnet source is 124 μm(H)×38 μm(V). The results obtained by this method can provide important references for measuring the electron source size and developing experimental methods with high requirements for uniform illumination.