Phosphorus slag could be used to prepare wollastonite glass ceramics. With the aid of incorporated foaming agent, foam glass ceramics can be obtained via the sintering of the slag-based glass. After the glass powder reacted with graphite, macro-size pores with homogeneous distribution were formed. The level of porosity of the fabricated foams was controlled by varying heat treatment temperature and amount of foaming agent. It was found that the preferential processing parameters for producing foam glass ceramics were foaming temperature of 1000°C with holding time of 10 min and 1 wt. % of graphite. In this case, the porosity reached about 80%. The results show that dominant crystalline phase is wollastonite, and the high compression strength results from the crystallization of glass during sintering process.