In this work, we first report on the radiation dose effect of -Al2O3:C crystal powder. The thermoluminescence(TL) and optically stimulated luminescence (OSL) of the powder are investigated by RisTL/OSL-DA-15. The as-grown -Al2O3:C crystal powder of same particle size shows a single TL peak and the TL intensity increases as irradiation dose increases, but no shift of the position of the TL peak is found, which is consistent with first-order recombination kinetics. And in the same radiation dose and test conditions, with the particle size of -Al2O3:C crystal powder decreasing, the TL intensity decreases after first increase and then the TL peak is gradually increases and approaches to a stable value, which shows that the -Al2O3:C crystal powder, 4060 m in diameter, has the best TL effect. The OSL decay curve of -Al2O3:C crystal powder shows the typical exponential decay characteristics, and the relationship between OSL intensity and decay rate with the particle size of -Al2O3:C crystal powder is found to be consistent with the shallow-electronic-trap theory.