OBJECTIVE： To study the inhibitory effect and mechanism of Inula helenium ethyl acetate extract （IHE） on proliferation of human pancreatic cancer Capan-2 cells. METHODS： MTT was used to determine the cell proliferation inhibition rate after treated by 0， 0.5， 1， 2， 4， 8 μg/mL IHE； clone formation test was used to observe the effects of 0， 1， 2 μg/mL IHE treating for 1 week on cell clone formation； Hoechest 33342 staining was used to observe the changes of nuclear morphology after treated by 0， 2， 4 μg/mL IHE for 48 h； flow cytometry was used to detect the cell apoptosis rate after treated by 0， 4， 8， 16 μg/mL IHE for 48 h； JC-1 staining was used to observe the changes of intracellular mitochondrial membrane potential after treated by 0， 4， 8， 16 μg/mL IHE for 24 h； Western blot was used to detect the expressions of mitochondrial apoptosis-related proteins Bcl-2， Bax， Mcl-1， p53 up-regulated modulator of apoptosis （PUMA）， and polymerase （PARP） after treated by 0， 4， 8， 16 μg/mL IHE for 48 h. RESULTS： 2， 4， 8 μg/mL IHE had obvious inhibitory effect on cell proliferation， showing concentration-dependent relationship， with IC50 of 6.6 μg/mL； 1， 2 μg/mL IHE can obviously inhibit the clone formation of cells； 4 μg/mL IHE can obviously cause cell nuclear condensation； 8， 16 μg/mL IHE can obviously promote the cell apoptosis， and the cell apoptosis rate reached 45.53％ after treated by 16 μg/mL IHE for 48 h； 16 μg/mL IHE treating for 24 h can cause the decrease of 82.47％ cells’ mitochondrial membrane potential； 8 μg/mL IHE can obviously down-regulate the protein expressions of Bcl-2， Mcl-1， PUMA and PARP， and 16 μg/mL IHE can obviously down-regulate the expressions of Mcl-1 and PUMA. CONCLUSIONS： IHE may show its inhibitory effect on proliferation of human pancreatic cancer Capan-2 cells by causing the decrease of mitochondrial membrane potential in cells and down-regulating the protein expressions of Mcl-1 and PUMA to cause cell apoptosis.