Abstract: Specific porous structures and heteroatom-doped adsorbents have great importance in improving the adsorption performance of heavy metal ions. Traditional porous organic polymer materials are mostly synthesized in solvents in the form of powder, so it is significant to develop a highly efficient adsorption material and apply it to the adsorption and removal of Hg(Ⅱ). In the research, S-doped porous organic polymer (TpTU) and chitosan (CS) composites TpTU@CS were prepared by using 1,3,5-trialaldehyde phloroglucinol (Tp) and thiourea (TU) by a simple and rapid mechanical grinding method. The TpTU@CS composites were characterized by X-ray diffraction spectroscopy, N₂ adsorption-desorption, scanning electron microscope and Fourier transform infrared spectroscopy. Due to the introduction of the −C=S− group into the molecular network, the synthesized TpTU@CS has high adsorption selectivity and affinity for Hg(Ⅱ) in aqueous solution, with high adsorption capacity (249.21mg/g) and fast adsorption kinetics (10min). Through the characterization analysis, it is concluded that the main mechanism of trapping Hg(Ⅱ) by TpTU@CS is the bonding between S and Hg in C=S and the coordination interaction between C−N and Hg(Ⅱ). Meanwhile, the composite TpTU@CS has a high removal capacity (77.0%−100.0%) of Hg(Ⅱ) for both the actual samples and the marked samples. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202211170219.