Three chemical flocculation methods including organic, inorganic and organic-inorganic composite were selected to treat slurry from construction engineering, in order to identify the mud-water separation process and to improve the mud-water separation efficiency. The effects of flocculant type (organic, inorganic and composite) and flocculant dosage on the mud-water separation process and its associated micro-mechanisms were compared through the indoor sedimentation column, particle grading and scanning electron microscopy tests. The experimental results show that the organic and composite flocculants can effectively promote the mud-water separation process, and the conditioning effect of organic flocculants is presented as follows according to the value of supernant volume: APAM>PAM>ACPAM>CPAM>HCA. The optimum performance of mud-water separation is identified at reasonable amount of APAM, and the water content of dewatered slurry is less than 76.8%. The effect of inorganic flocculants on mud-water separation is relatively poor, when compared to organic and composite flocculants. The combined formulation of FeCl₃ and APAM can improve the conditioning performance of slurry, and play effectively the role of electro-neutralization and net capture-sweep. The flocculant caused an obvious agglomeration of fine particles in slurry through adsorption bridging, leading to a reduction in fraction of fine particles and an increase in amount of agglomerated coarse particles. The scanning electron microscopy images reveal that the original slurry particles tend to be deposited in a parallel manner, and the flocculant induces an agglomeration of fine particles and a denser flocculated microstructure. This study reveals the intrinsic microscopic mechanism of flocculation-induced mud-water separation process, and provides a theoretical basis for rapid mud-water separation technology of waste slurry from construction engineering.