Abstract: The main method of carbon retract from blast furnace sludge was got by flotation with diesel or coal oil as collector and 2^# oil as foaming agent.But different flotation result was got for the different properties of blast furnace sludge.In this paper, orthogonal test was designed to research the effect of the main factors on the basis of the analysis of range.The results showed that pulp concentration and dosage of efficient flotation reagents have the maxium effect on the carbon content of concentrate and recovery.This research provides basis data for the application of similar blast furnace sludge to some extent.