Amidoxime polyacrylonitrile (AOPAN) beads with diameter of around 2 mm were prepared by a simple ball-dropping method, and were used as support for the immobilization of Pd or PdNi nanoparticles for catalytic application in formic acid dehydrogenation. The Pd-based nanoparticles showed uniform distribution on the surface of the AOPAN beads, with good accessibility to reagents. The optimized PdNi/AOPAN catalyst can efficiently convert formic acid to hydrogen with a turn over frequency of 3041 h-1 under ambient conditions, and this catalytic activity was maintained well for at least seven cycles. The millimeter-sized beads can float on water, making them easy to manipulate and recover without any weight loss. The amidoxime and cyano groups on the surface of the AOPAN beads play critical roles in stabilizing and distributing Pd-based nanoparticles, and may also participate in the synergistic activation of formic acid dehydrogenation.