Abstract: The vertical cracks usually appear in the unburned brick masonry wall beneath the window opening of the ground floor. The cracks are generally due to the volume shrinkage of masonry wall, which is constraint by the foundation or the ground. In order to explore the cracking mechanism, the effect of volume changes of masonry wall was investigated in the context of elasticity theory in plane stress condition by the stress function method. The hypothesis of the restraint actions in the horizontal direction between the ground and the masonry wall was proposed, and the simpler stress analysis method of volume changes was obtained according to the hypothesis and the boundary conditions of the masonry wall. Then the stress distribution of the masonry wall restricted by the foundation or the ground was obtained. The maximal horizontal tensile stress and the movement joint spacing of masonry walls were studied, and compared with the provisions in Chinese Code.