Combined with the injecting waste plastic into BF technology, LCA methodology was used to do analysis of the energy consumption and CO2 reduction of main products in steelworks. After injecting waste plastic into BF, the energy consumption of hot metal, hot rolling coil and cold rolling coil will have small increase in the boundary of steelworks. With a higher proportion of injection,the rate of increase is increased. The energy consumption of steel product will decrease in the boundary of whole life cycle. The rate of decrease is reduced with increasing injection ratio. The CO2 emission of hot metal, hot rolling coil and cold rolling coil will decrease both in the boundary of steelworks and the whole life cycle. Along with higher injection ratio, CO2 emissions reduction rate will be rapidly increased.