Adsorption stands for a promising technique for heavy metal remediation. Herein, a high efficiency adsorbent based on magnetic chitosan-graphene oxide (MCGO) was prepared via a simple co-precipitation procedure. Afterwards, adsorption behaviour of Pb(Ⅱ) on MCGO surface was illuminated via batch adsorption experiment and statistical physics calculation. Result presents, MCGO reaches adsorption percent and adsorption quantity 93.06 % and 372.24 mg·g−1 for Pb(Ⅱ) in 44 min, showcasing favorable remediation efficiency. Statistical physics calculation proposes multi-ionic adsorption mechanism. With the increase of temperature, adsorption site density is increased to yield ameliorated adsorption capacity. Moreover, calculation result of the thermodynamic functions designates exothermic, randomness increasing, spontaneous and energy releasing feature. Kinetic fitting based on various models assigns chemical interaction as the rate controlling step. Finally, adsorption mechanism was clarified in atomic level via spectroscopic inspection. Specifically, C=O, C–O, O–H, N+ and –C(=O)NH– contribute to Pb(Ⅱ) adsorption via donating lone pair electrons. This work provides both experimental and statistical physics insights for understanding the adsorption behaviour of typical heavy metal pollutants onto the surface of bio adsorbent like magnetic chitosan-graphene oxide.