In the current study, thermoplasmonic characteristics of Erbium nanoparticles with spherical, core–shell and rod shapes are investigated. In order to investigate these characteristics, interaction of synchrotron radiation emission as a function of the beam energy and Erbium nanoparticles were simulated using 3D finite element method. Firstly, absorption and extinction cross sections were calculated. Then, increases in temperature due to synchrotron radiation emission as a function of the beam energy absorption were calculated in Erbium nanoparticles by solving heat equation. The obtained results show that Erbium nanorods are more appropriate option for using in optothermal human cancer cells, tissues and tumors treatment method.