Three kinds of novel macromolecule flocculant, called polyethyleneimine-sodium xanthogenate (PEX), were prepared by chemical reaction to graft dithiocarboxylic groups onto three different molecular weights of polyethyleneimine. The removal performance of turbidity by PEX was studied with two different types of turbidity-containing water samples through using flocculation experiments. The results showed that the three kinds of PEX had different removal properties for turbidity with the different turbidity-containing water samples. The highest removal efficiency of turbidity increased with the increase of the molecular weights of PEX, and slightly increased with the increase of the original turbidity of water samples. When pH value of the water samples reached the isoelectric point (pH_iep) of PEX, the removal rate of turbidity was highest, and reached 98.6%, 96.6% and 91.3% at pH_iep of 3.8, 5.0 and 8.7 for PEX-1, PEX-6 and PEX-60, respectively. The removal efficiency of turbidity was obviously improved with the coexistence of Cu(Ⅱ) or Ni(Ⅱ) in the water samples. The residual turbidity decreased or increased with the decrease or increase of the absolute value of zeta potential in the system.