Abstract: Several supported palladium catalysts were prepared and thier effects on the kinetic behaviors in the selective hydrogenation of cyclopentadiene were studied. Experiments show that cyclopentadiene inhibits the hydrogenation of cyelopentene. Data based on kinetic analysis indicate that the coordination of cyclopentadiene is much stronger than that of eyclopentene which should be the main factor of this inhibition reaction. Catalyst carriers via thier ligand effects can influence the ratio of the coordination equilibrium constants K_D/K_E and the rate constants k_2/k_4, which in turn change the selectivities and activites of catalysts.