Abstract: As the semi-coke prepared with coal slime is high in ash and fine in size,flotation process is applied for its upgrading and ash reduction. An investigation is made in the paper of the effect on ash reduction of semi-coke produced by agent regime and number of stages of flotation concentration process.Test result indicates that: the use of activator X-100 can yield a notable result in this respect; concentrate ash cannot be effectively reduced by simply increasing the number of concentration stages; and a best flotation result can be expected under the following optimum working conditions: dosage of kerosene -1 200 g/t,dosage of X-100-200 g/t,dosage of frother 2-octanol -100 g/t and density of feed pulp -60 g/L; under the condition as stated above,through only one rougher process,an upgraded semicoke product with a yield of 75.62%,an ash of 21.08% and a recovery rate of combustible matter of 82.40% can be obtained; and the ash of semi-coke is reduced by 6.34%,much raising its value for comprehensive utilization.