Laboratory tests were performed to investigate the influence of reactive MgO mixing amount on compressive strength, its characteristics and durability of the carbonization blocks. The results show that the compressive strength of the carbonization blocks increases from 014d of carbonization, while it decreases slightly from 1428d of carbonization. The compressive strength of the carbonization blocks with 35% amount(by mass) of reactive MgO is significantly higher than that of 15% and 25% amount of reactive MgO. The carbonization products of reactive MgO are mainly hydromagnesite, nesquehonite and dypingite. More carbonization products and denser texture are observed in carbonization blocks with the higher amount of reactive MgO. The durability of the carbonization blocks with 35% amount of reactive MgO is better than that of 15% and 25% amount of reactive MgO.