Abstract: Objective To investigate the influence of Procaine hydrochloride(PCA) on human colon cancer HT-29 cells proliferation and explore its mechanism. Methods HT-29 cells were treated with 0~10mmol/L of PCA，cell morphology changes were observed under contrast microscope.Cell proliferation was detected by MTT assay and cell cycle was detected by fIow cytometry (FCM ). Results With different concentrations of PCA being used to dispose cancer cells separately，growth inhibition taking the form of cell's decreased size，shrinkage，vacuoles，cells abscised from the inner surface of the bottle became increasing obvious under contrast microscope. With the rise of the PCA concentration,HT-29 cells has a presentation of negative acceleration in the proliferation by MTT.The analysis of the result indicated that PCA can inhibit the cell proliferation significantly whose effect was replying on the dosage and time.The result by FCM shows that PCA can lengthen the G0/G1 phase and shorten the S phase in HT-29 cells. Conclusion PCA can make the growth of the HT-29 cells blocked in G0/G1 phase ，thus inhibiting the cell multiplication significantly,whose effect was relying on the dosage and time.