Non-linear analysis of autoclaved aerated concrete (AAC) block masonry composite wall with reinforced concrete (RC) core columns has been conducted using finite element software ABAQUS. First, the numerical results from finite element analysis were verified with laboratory results of full-scale AAC masonry wall specimens. Effects of vertical stress on seismic performance were investigated. The analysis indicates that lateral load capacity of the wall is affected by the openings greatly and increased with the increase of vertical stress. The effect of vertical stress on the wall without openings is more obvious than that with openings.