Thermoregulated phase-separable Pd nanocatalyst exhibited high performance in the selective hydrogenation of α, β-unsaturated ketones at atmospheric hydrogen pressure. Under optimized reaction conditions, the conversion and hydrogenation selectivity of the C=C bond for chalcone were >99%. The catalyst can be easily separated from the product and recycled seven times remaining >99% conversion and selectivity. The turnover frequency (TOF) was up to 1470 h-1, which exceeds the value reported in literatures for the selective hydrogenation of chalcone catalyzed by transition metal nanocatalysts under atmospheric hydrogen pressure.