The thermal behavior of different boron powder coated with AP and LiF was investigated by means of DTA-TG. The effects of coating and agglomeration on combustion heat of agglomerated boron and explosive heat of boron based fuel-rich propellant were studied. The results show that boron coated with AP promotes the oxidation degree of boron in oxygen environment while boron coated with LiF reduces the temperature of boron oxidation. The coated boron has improved combustion and released more heat. Small particle size of agglomerated boron is beneficial to boron combustion.