Abstract: A lead-zinc mine has certain requirements for the strength of the tailings particle floc. In order to study how to characterize and increase the floc strength, the shearing environmental factors such as the type and dosage of flocculant, stirring time, stirring speed, and input energy per pulp were investigated. The effect on the shear flocculation sedimentation of a lead-zinc tailing was tested by corresponding flocculation sedimentation test, particle video microscopy (ParticleView V19) real-time monitoring and microscopic floc image analysis. And the flocculation mechanism was discussed in order to reveal flocs relationship between formation process and flocculation effect. The results showed that the flocculation effect of flocculant on the lead-zinc tailings from strong to weak was as follows: cationic polyacrylamide> anionic polyacrylamide> cationic etherified starch. The optimal dosage of cationic polyacrylamide (CPAM) was 200 g/t. PAM could reduce the kinetic potential of the particle surface and agglomerate. When the flocculant dosage was excessive, the entire system became positively charged. Due to the mutual repulsion between the positive charges, the floes were dispersed again, and the re-stabilization phenomenon was occurred, which could weaken the flocculation effect. Stirring time, stirring speed, and unit pulp input energy had a great influence on the shear flocculation behavior of the lead-zinc tailing. The stirring time was related to the growth and fragmentation of the floc. The stirring intensity was related to the shear strength of the floc. The greater the stirring intensity, the higher the flocculation final stable shear strength and the more regular the morphology were. There was a limit value for the unit pulp input energy. When the limit value was exceeded, the floc formation and fragmentation reached a relatively balanced steady state, and the floc could exist stably under this stirring system.