The magnetic entropy around the paramagnetic–ferromagnetic (PM–FM) phase transition temperature TC has been investigated for chromium based spinel CdCr2Se4. It is found that magnetic entropy changes are generated by the spin–lattice coupling, which can be easily modulated by the external magnetic field. The electron paramagnetic resonance (EPR) study proves the existence of the spin–lattice coupling above TC, and reveals the stronger coupling at TC. In addition, the variation of the micro-structure due to the spin–lattice interaction has been observed around TC from the measurement of the low-temperature X-ray diffraction.