Objective To study the effects of PU-H71 on the proliferation, apoptosis, cycle and other biological behaviors of colorectal cancer HCT-15 cells, and to explore the mechanism of apoptosis and cycle at the molecular level. Methods HCT-15 cells were cultured in vitro. The effects of PU-H71 at different time and concentration on the proliferation of HCT-15 cells were examined by MTT assay. The apoptosis and cell cycle of HCT-15 cells were examined by flow cytometry assay, western blot was used to detect the expression of apoptosis and cycle-related factors. Results After 24h and 48h treatment, PU-H71 showed significant inhibitory effect on colorectal cancer HCT-15 cells in time and concentration dependent manner. After treatment with PU-H71 at two concentrations of 50μg/L and 75μg/L without drug for 24h, the apoptosis rate of HCT-15 cells increased and the proportion of G2 phase cells increased. The protein expression levels of STAT3 and JAK2 were significantly decreased, the protein expression levels of CyclinD1 and Bcl-2 were decreased, and the protein expression levels of Cytc, Caspase9, Caspase3, and Bax were up-regulated. Conclusion PU-H71 can significantly inhibit the proliferation of colorectal cancer HCT-15 cells, arrest the cell cycle in G2 phase and induce cell apoptosis. PU-H71 may regulate the mitochondrial signaling pathway by negatively regulating the JAK-STAT3 pathway, thus affecting the expression of apoptosis and cyclic-related factors.