Abstract: This paper studies the several key parameters of the foam seperatation humus from black water of grass pulp.According to the results of tests:the best technological parameters of separation are the square of flotation container to the square of draught aerator is 2￣3:1;the tength to diameter of flotation container is 2∶1;gas to solid is 0.028.In addition,the preliminary analysis in technical economy for both methods indicates that the flotation method is better.