Prussian blue analogue nickel ferrocyanide (NiPB) decorated carbon nanotube sponge (CNT sponge) was prepared as a newly designed spongiform adsorbent. This composite material was characterized by scanning electron microscopy (SEM), inductively coupled plasma (ICP) and tested in adsorption experiments. Results show that the CNT-NiPB sponge was equipped with large holes and porous structure, a large number of MWNTs and NiPB particles uniformly deposited on the surface and internal cavities. This adsorbent CNT-NiPB sponge showed a good adsorption selectivity of cesium and strontium in mixed aqueous solution, which is mainly induced by the ion exchange reaction of NiPB and metal ions. The novel spongiform adsorbent might have a promise prospect in radioactive wastewater treatment applications.