Abstract: An analytical study is made in the paper of the parameters involved in the emulsification of diesel oil using colloid mill. It is observed that at an oil-water ratio of 5 ∶1,an optimal emulsifying result can be attained. Comparative test is made on the use of emulsified diesel oil and diesel oil as collector.Test result indicates that with the use of the former as collector,the flotation perfection index is 5. 66 percentage points higher,and the yield of concentrate in the first time is also increased by 5. 01 percentage points as evidenced by result of test on flotation rate. Under the condition that flotation is made with identical flotation perfection index,the consumption of emulsified diesel oil is lower than that of diesel oil by 39. 13%.