At present, masonry and plaster of AAC blocks are still carried out by traditional construction methods which often lead to some quality defects such as cracking and leaking in the wall and hollowing and spalling in the plaster layer, etc. and hinder greatly the popularization and application of AAC blocks. On the basis of the characteristics of AAC blocks and the dry masonry thin-bed mortar, a kind of high performance dry-mixed Mortar for dry masonry process of AAC blocks was developed. The mortar has excellent workability, high water-retention, property, good mechanical properties and good construction properties. It solves the problems caused by traditional construction methods. The mechanism for these is discussed.