To overcome the shortcoming of traditional masonry mortar for air -entrained concrete such as poor water retention, low bonding strength and liabititv to cracking, a new type masonry mortar for air-entrained concrete with better performance than that by JC890 -2001 standard was prepared. The effects of water-retentive agent, redispersible latex powder and expansive agent on masonry mortar were studied, and their modified mechanisms were discussed respectively.