The influence of Sn on the activity and selectivity of Pd catalysts for the hydrodechlorination (HDC) of 4-chlorophenol (CP) in an aqueous phase was studied. The Pd–Sn bimetallic catalysts were prepared using the coimpregnation method and characterised using temperature-programmed reduction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen pulse chemisorption measurements. The results showed that when the molar ratio of Sn/Pd is less than 1/1, the addition of Sn to Pd catalysts improves the dispersibility of Pd particles and improves the catalytic activity of HDC.