By means of investigation on serious damages and collapses of a large number of masonry structures due to 5. 12 Wenchuan earthquake, it has been found out that the seismic intensity in a hardest hit area was greater than or much greater than the intensity of housing security is the main reason, followed by unreasonable design, poor quality construction and other reasons. It is pointed out that the matters needing attention in the design and construction of the structures, which may be a reference for engineers and construction staff.