Abstract: The treatment of ¹³⁷Cs radioactive waste water is of great importance in the application of nuclear energy and nuclear technology. In this work, one-dimensional structure Prussian blue was synthesized by using surfactant as template, and it was loaded on the surface of diatomite to prepare Prussia blue/diatomite composite material. The performance of one-dimensional Prussian blue/diatomite composite adsorbing Cs⁺ was investigated under different temperatures, adsorption time and pH values. The effects of other cations on adsorption were also studied. The results show that the adsorption capacity(from 42.4 mg/L to 61.6 mg/L) of one-dimensional Prussia blue/diatomite increases with temperature(from 293 K to 318 K). The adsorption behavior is consistent with Langmuir isotherm model and pseudo-second order kinetic equation.