To study the effect of three aspects such asmortar strength, of opening rate and ratio of height and width on thestiffness degradationof masonry bearing walls,the paper took the bottom walls of a 3-story masonry structure as prototype,and designed four scaled wall specimens to carry out pseudo static test.The results show that the stiffness degenerates quicklyat the preliminary stage of loading. The influence of every factor is similar.The stiffness degradation slows downafter cracking of test-piece.Thecoefficient stiffness degradation at some feature points such as crack load, ultimate load and failure load is respectively about 76%, 20% and 16%. The lower the mortar strength,the poorer the viscidity of mortar.Thelessthe initial stiffness,the slower the stiffness degradates after cracking,theplastic deformationof test-piece is small. The lager ratio of openings, the smaller initial stiffness.thestiffness degradation intensify after cracking.The plastic deformation is the minimum. The larger the ratio of height and width, the less the initial stiffness,the stiffness degradation is the minimum. Theresult can provide reference for further research of effect of every factor on stiffness degeneration of masonry wall.