Abstract: A simple functionalization method has been developed to modify hydroxyl groups in cellulose by facile chlorination and aminolysis approaches. The thiosemicarbazide group modified straw cellulose can be finally formed and experimentally confirmed by the Fourier Transform Infrared spectrum and energy dispersive spectrometer. As adsorbent for Hg(Ⅱ) adsorption from water, the results demonstrated that the thiosemicarbazide modified cellulose possessed high performance for Hg(Ⅱ) adsorption from water with a high adsorption capacity of 499.6 mg/g. The sorption model followed Langmuir model and pseudo-second order kinetic model. The fitting coefficient (R2) was more than 0.98. The enhanced Hg(Ⅱ) adsorption capability of thiosemicarbazide modified cellulose could be attributed to chelating interactions of Hg(Ⅱ) with thiosemicarbazide functional groups.