In this work, chitosan with deacetylation degree of 81.3% was prepared by deacetylation of chitin extracted from crab shells with the yield of 50.1%. By stirring and cross-linking with glutaraldehyde, chitosan gel particles with the size of about 5 µm to 20 µm were prepared. Some characteristics of chitosan and chitosan gel particles were investigated by FTIR, SEM, TGA, XRD,…. The adsorption capacity of Pb2+ ion was investigated with Langmuir, Sip and Freundlich isotherm adsorption models. The results showed that the chitosan gel particles adsorbed Pb2+ ions consistent with the Freundlich isotherm model and after 24 hours of sample treatment, the Pb2+ content in the solution decreased by 96,39%.