Pd nanocatalysts were successfully synthesized by the ethylene glycol reduction method using graphene as supports and applied to the selective hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN). The results indicate that the low transfer resistance and strong metal-support interactions between RGO and Pd nanoparticles of Pd/RGO can efficiently improve the selectively. The low transfer resistance can shorten the stay time of the product molecule o-chloroaniline (o-CAN) on the surface of the catalyst sites and then reduce the dechlorination side-reaction of o-CAN. The strong metal-support interactions can lead to the electron-deficient state of the Pd nanoparticles which weakened the extent of electron feedback from the Pd nanoparticles to the aromatic ring and suppressed the hydrodechlorination of o-CAN. Moreover, the selectivity can be further improved for the hydrogenation of o-CNB after grafting sodium polystyrenesulfonate on the Pd/RGO to cover the low-coordinated surface Pd atoms.