Novel selective nanoadsorbents should be well developed to eliminate chloramphenicol efficiently in aquatic environment. In this research, we reported novel, well-defined core-shell surface imprinted nanospheres with ultrathin polymer film based onto magnetic mesoporous nanosilica (MMSNs@MIPs) with the similar structure of pitaya via a facile in-situ precipitation polymerization, which was used as an advanced selective nanoadsorbent to remove chloramphenicol. SEM, TEM, VSM, XRD, TGA and FT-IR were characterized to analyze the physical-chemical property. Magnetic nanoparticles were uniformly dispersed into the pore of mesoporous silica. The imprinted nanoshell was uniform and ultrathin, with the thickness of 9.0 nm. MMSNs@MIPs had a large adsorption capacity of CAP and reached the equilibrium rapidly within 30 min, owing to mesoporous nanosilica core and ultrathin imprinted nanoshell. The increase in temperature enhanced adsorption capacity and kinetics, indicating the adsorption process was endothermic reaction. Adsorption isotherms and kinetics data could be better fitted by Freundlich model and the pseudo-second-order rate equation, respectively. The selective nanoadsorbent exhibited highly specific recognition to template CAP from water solutions as compared with other reference antibiotics. MMSNs@MIPs also possessed a fast magnetic separable ability and good thermal stability for the potential application in water treatments. (C) 2015 Elsevier B.V. All rights reserved.