In this work, the effect of chain length of xanthate on the flotation performance of Jinchuan nickel ore was studied by different pre-flotation conditioning methods. Results showed that the presence of serpentine minerals in the ore interferes with the flotation performance of pentlandite. Two methods were used to eliminate the adverse effect of serpentine slimes and improve pentlandite flotation performance. Compared with the addition of Calgon, High Intensity Conditioning (HIC) could increase pentlandite flotation recovery significantly. Three kinds of xanthate with different chain length were used as collectors. When HIC is used at the conditioning stage, the longer the hydrocarbon chain of xanthate, the lower the Ni recovery, while when Calgon is used at the conditioning stage, the longer the hydrocarbon chain of xanthate, the better the pentlandite flotation performance. (C) 2012 Elsevier Ltd. All rights reserved.