Cr， In co-doped MgGa2O4 persistent luminescence nanoparticles（PLNPs） with small-size were prepared by ethylene glycol assisted co-precipitation. The influence of Cr，In co-doping and calcination temperature on the MGO crystal structure， afterglow luminescence properties and size were further investigated. The results showed that the optimal Cr，In co-doped concentrations were 0.3% and 0.02%， respectively， and the samples belonged to Fd3m space group， Cr，In co-doping had no effect on the structure of the samples. The PLNPs had a good water dispersibility with an average particle size of （8.61±2.23） nm and the optimum calcination temperature of 700 ℃. Moreover， the afterglow decay life was prolonged by In doping， and the average luminescence life（τav） of the afterglow decay fitting curves increased from 49.33 s to 52.89 s with the QY increased to 44.9%. The activation energy（Ea） was （0.36±0.04） eV. The PLNPs had a good thermal stability， and the trap depth was 0.696 eV. Moreover， the PLNPs had three excitation bands at 260， 410 and 600 nm， respectively， which indicated that UV light， blue-green light and red light could be excited， and the emission wavelength was all at 705 nm， belonged to the 2E（2G）→4A2（4F） transition of Cr3+. Therefore， the PLNPs had a great potential application value in red LED lamps， optical storage devices and biomedical fields.
