Since there are no studies on the reversal of multidrug resistance by curcumin in the human colorectal cancer cell line HCT-8/5-FU, our aim was to search for highly efficient reversal agents and investigate the underlying mechanisms of this reversal. The cytotoxic effects of curcumin and 5-FU on HCT-8 and HCT-8/5-FU cells and the reversal effects of 5-FU in combination with curcumin on HCT-8/5-FU cells were measured using cell counting kit-8. Apoptosis and the cell cycle were analyzed by flow cytometry. Protein and mRNA expression levels of BCL-2, survivin, P-gp, and HSP-27 were detected by western blotting and quantitative real-time reverse transcription polymerase chain reaction, respectively. Curcumin inhibited the growth of HCT-8 and HCT-8/5-FU cells. It significantly reduced the IC50 of 5-FU for HCT-8/5-FU cells (P < 0.01) and the expression of BCL-2, survivin, P-gp, and HSP-27 in the cells. Curcumin can effectively reverse multidrug resistance in human colorectal cancer drug-resistant HCT-8/5-FU cells. The mechanism through which this occurs may be associated with decreased expression of BCL-2, survivin, P-gp, and HSP-27. Curcumin may therefore have clinical implications as a new agent for colorectal cancer.