Meishan Steelmaking Plant adopts BSSF technology to deal with BOF slag， after that the proportion of slag with granularity less than 5mm is about 85%. BSSF slag is a sort of pre-melting slag， which composition is CaO， SiO 2 ， FeO， and has many characteristic such as low melting point， high alkalinity and high oxidability. BSSF slag used as slag-forming element can promote the slag melt rate of prior period， improve alkalinity and oxidation， lower cost. Meishan Steel has effectively explored recycle of BSSF. The practice shows that after using BSSF， lime consumption per ton steel decreases 6.5 kg/t， terminal slag alkalinity improves 0.3，phosphorous partition ratio in- creases 5.3 and its fluctuation range gets narrow， consumption of ironscrap charging reduces 4.6 kg/t.