Objective To investigate the effects of crocin on the proliferation and ERK1/2 pathway in human umbilical vein endothelial cells (HUVECs) in vitro. Methods In this study, HUVECs were treated by crocin with or without the MAPK/ERK kinase(MEK) inhibitor PD98059, and the proliferation of cells was measured by EdU assay. The expressions of phospho-ERK1/2 (p-ERK1/2) and total-ERK1/2 (t-ERK1/2) were analyzed by Western blotting. In addition, the concentration of intracellular Ca²⁺ was detected by confocal microscopy to evaluate the underlying effect of crocin on the cell proliferation. Results EdU assay showed that crocin stimulated the cell proliferation effectively, especially at the concentration of 1μmol/L and 10μmol/L. Western blotting results revealed that crocin improved the expression of p-ERK1/2 and t-ERK1/2 in HUVECs. The increase of the intracellular Ca²⁺ concentration by crocin at 1μmol/L and 10μmol/L concentration was importantly declared using Fluo3AM labeling. After the inhibitor of MEK PD98059 was given, decreased the level of cell proliferation, and the p-ERK1/2 and t-ERK1/2 expression and the intracellular Ca²⁺ concentration had decreased as well. Conclusion Crocin has effect on the proliferation of HUVECs and increase the intracellular Ca²⁺ through ERK1/2 signal pathway.